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TerribleDamage
07-31-2014, 10:39 PM
Hey all. After years of wanting and saving, I have purchased a CNC machine! Since I don't have a precision mill, making one myself was out of the question, so I finally ordered a CRP4848 kit, legs, and electronics from CNCRouterParts. In total, the order was over $5,000 before shipping. I was so excited!

Unfortunately, I ordered the machine and parts over a month ago, and all I have received so far are aluminum extrusions from some third party company. That's right, 136 pounds of aluminum, sitting on my dining room floor doing nothing, for a month. The guy from CNCRouterParts emailed me once a long time ago with an update, saying he had no idea when the rest of the order would ship. Great update. Then another email when he told me it would ship in 5 to 10 days. Well, that email was 10 days ago, still nothing else shipped.

So I guess I'll review the parts I have already. First of all, the aluminum doesn't look precision milled at all. From the tool markings, it looks like they just used some sort of circular saw to cut the aluminum. Ridiculous! See the attached picture. What is the precision going to be from that, .063 inches maybe? I was hoping for 0.001 inches. Maybe I'm naive, but I thought parts would be precision machined for $5,000+ orders. Next, look at the holes drilled and tapped into the aluminum. I don't need calipers to see that some guy just eyeballed it. No precision machining or drilling whatsoever. Very disappointing. Of course, the aluminum hasn't even been deburred. Super. The entire reason I bought a CNC machine is because I don't have the tools to machine precision parts...and this is what I get?

I'll continue posting pictures and updates if and when I ever get the rest of the parts. I am most fearful for the linear motion component. I am hoping the ground rails will be accurate enough, that is my biggest fear. The pro machine was out of my price range, so this one will have to do. I'll post accuracy measurement when I have them. So far though, I'm disappointed in CNCRouterParts. Not just for zero quality control, but also for not shipping my order for over a month. If I would've known that, I would've bought elsewhere.

nlancaster
07-31-2014, 11:40 PM
Terrible, I ordered a CRP4848 and it took almost exactly 3 weeks for all the parts to show up. This information on believe was relayed to me on the confirmation email, that shipping was 2-3 weeks. The aluminum showed up only 1 week after ordering for me. If you want an update on the order just shoot them an email I am sure tehy can give you an update.

cgo
08-01-2014, 12:05 AM
Not defending them at all, but it was probably cut on a cnc cold saw which is the fastest way to cut that material, you will probably not see the finish after its built and if the saw if setup right it will be accurate.

The tapped holes I would use a horizontal mill to tap them.
You can check the taps by screwing some long bolts in and see if there are even with a square, same with the cuts.
If there not debured you can use a counter sink to clean the edges of the tapped holes easy enough.

Even without inspection tools you can still get an idea how well the parts are made.

TerribleDamage
08-01-2014, 12:49 AM
I'm not so much concerned about seeing the finish as I am about accuracy, and for that reason, I'll definitely have to deburr it. Not just the holes, but all the internal edges so it can be flush with whatever it intersects. I hope you're right about it being accurate.

That's a good idea, once I get some bolts, I can check if they're square with a nice, precision square...but unless it is some weird optical effect or something, there is no way those holes are square.

My confirmation email never specified shipping time, but I remember either just before or after the order completed, the website said it would take two weeks. But we're double that now, I mean, I ordered this thing in late June, tomorrow will be August :p I wish they could have just sent the legs, or the smoothstepper, or something to keep me busy while waiting. I don't mean to sound too grumpy...I'm just annoyed and needed to vent :p

ahren
08-01-2014, 02:16 AM
Hey Terrible,

First of all, I'm very sorry it has taken so long to deliver the rest of your parts -- we got absolutely slammed with orders in June, which has traditionally been a slow month for us. We've been adding people to our staff and working to increase inventory, but are still struggling to catch up. I'll look into your order personally tomorrow to try and get things moving for you. You're completely justified in venting, and I apologize for the lack of communication on your order.

The extrusion you received is cut on a automatic aluminum jump-saw, which is pretty typical and is usually quite accurate in terms of length and squareness. As to the tapped holes, the holes themselves are actually formed during the extruding process, and they are then tapped (there is no additional drilling), so they are inherently parallel to the extrusion. I agree the 8020 factory could have done a better job deburring, and we'll talk to them about this, but I don't think you should have any functional issues with your assembly, especially since the tapped holes really only hold the bumpers for the machine.

We want you to have a good experience with your machine build, and I'm sorry we haven't lived up to that so far -- we'll definitely get things going for you as quickly as we can.

Best regards,

Ahren
CNCRouterParts (http://www.cncrouterparts.com)

CYoung
08-01-2014, 10:14 AM
I ordered the PRO4848 back in May and it took about 3 weeks for everything to arrive which beat the quoted 4 week lead time. I think these guys are very honorable and will ultimately make you satisfied with their product....just my two cents

pete1961
08-01-2014, 10:31 AM
That is typical for 80/20. Not saying it is bad at all but it is normal for them to cut material and drill that way. I built a PRO2448 and all of my extruded material went together perfectly even after having it look as yours does. You will have to be carefully precise as you assemble the 80/20 material on your build no matter anyway. It should all go together fine provided everything is carefully assembled.

BuckNaked31
08-01-2014, 11:06 AM
Your extrusion comes from 80/20, not CNCRouterparts. In all my dealings with CNCRP, I can say that I've always received my parts quickly, sometimes shipping the same day. I'm a huge fan having owned a machine made from their parts for several years. If you don't like their parts, send them to me... I'll put them to good use :) P.S I just ordered a part from them this week... got here in 2 days and I'm in Texas!

Sent from my LGMS769 using Tapatalk 2

Rebelac
08-01-2014, 12:19 PM
I just assembled my extrusion early this week and it was less than 1/16" out of square. I don't see any way of getting it perfect without a lot of work with shims. The corner brackets pretty much dictate the position and square-ness.
After finally getting the gantry squared up, it compensates for the base being off. I mounted the motors on the x-axis last night and everything seems to remain square. I'll find out when I'm able to make some cuts. I'm sure there are some adjustments that can be made to get it cutting fairly square if it's needed.

TerribleDamage
08-01-2014, 03:34 PM
Hi all, I have an update! I spoke to Cory on the phone this morning, and I've just received 4 tracking numbers. Looks like most of the parts are now on their way, so I'm happy :)

As far as squareness goes, I'll likely check the squareness of everything at every step of construction with an INCRA precision square. I'm hoping to beat even 1/16th inch...even though is sounds small, over 48 inches, that is still over a thousandth of an inch off per inch.

groc426
08-01-2014, 04:48 PM
Just got 95% of my cnc put together from cncrp. My experience has been nothing but outstanding. They are extremely professional and their products have reflected that. Im glad to hear they've gotten you taken care of though.

MobiusConcepts
08-04-2014, 09:52 PM
Hmm, I'm not sure you understand the meaning of the word 'epic' TerribleDamage....

TerribleDamage
08-05-2014, 12:06 AM
Hehe, big things have small beginnings...But 4 packages are finally arriving tomorrow. 36 days was a long time to wait, but hopefully it'll be worth it. I actually tried to go back to make the original post a little nicer, but couldn't find any way to edit it. Oh well, I'll post some pics and measurements as the build progresses.

TerribleDamage
08-10-2014, 02:55 AM
Hey all, just an update :) My beautiful router is starting to take shape. Everything so far is very level, and the largest error from rail to rail is less than 1/64th inch near the very back, but for most of the distance, I couldn't measure any error. It took a ton of time to get that precision though. I made some pretty big mistakes that cost a lot of time. Some things I've learned:

1) Don't bother spending time squaring the legs, since you'll just have to loosen it up and expand it to fit the base of the router later.
2) Assemble the base (with 2 or 3 supports is good enough) on the floor, not up in the air on those legs. Use a precision square for every beam.
3) Definitely use pipe clamps to make sure the beams are flush. I redid the base because I later measured it was off by 1/32" at one end when measuring across. But after that, I couldn't measure any error in the metal frame at any point.

Other thoughts...I'm not sure how much I trust the legs, I'll reinforce them later. No matter how tight those bolts are, they still shift around, then I have to re-level the base. Also, I think they could use a second bolt at the top of each leg. With just one bolt, they swizzle way too easily. Also, having the legs fully supported with a diagonal and horizontal beam for every side will make them much more solid. I don't include the machine base, since those top joints swizzle.

One problem...the racks I got were 52.125", but in the assembly drawings and 3d model i saw they were 54". Because of that, I didn't know exactly where to put the rack supports with respect to the ends of the machine...so I just split the measurement difference at each end...hopefully that's okay.

I also found 4 curious little pieces of metal in the bumper bag for CRP110...Not sure what to do with them, so I just guessed, lol.

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Rebelac
08-10-2014, 10:39 AM
You need to measure your table on the diagonal to determine square, measuring across only determines if the frame sides are parallel.
The shortened racks are one of the infamous changes that have been made and not documented. Since you centered them, you will be removing(loosening) them and repositioning them. Another great feature of their documentation.
The little metal plates you refer to, I believe it's the plates you have behind your bumpers in the pic, are for the prox switches and go on the backside of the bumper bracket. Yes, more of that wonderful documentation.
Good luck moving forward.

ahren
08-10-2014, 12:04 PM
Hi Terrible,

You've done a great job getting your base together -- the most important thing is to have the two steel rails parallel to each other. Everything else can be handled later, and if you setup dual homing switches on the X and X slave (recommended) you can auto-square the gantry every time you home the machine. We have one customer who put their machine base together quickly and ended up with one bumper was offset from the other by almost 1/2". He didn't bother to fix it and still cuts exceptional (and large) workpieces on a CRP4896 using dual homing switches. Not saying this is the best approach, but you don't need to stress about this too much.

The 52" racks provide more than enough travel for the machine since the gear only touches the rack at one point, so placement doesn't need to be precise. When you mount the rack and pinion drives you will notice that the pinion gear is biased to one side -- you just want to bias the rack in this direction. The actual spacing of the rack clamps isn't too critical either.

The extra brackets in the bumper kit were included by mistake -- they are for the prox switches, but you have a newer X bumper design which already has tapped holes for M12 threaded prox sensors, so you don't need the brackets if you decide to add switches later.

Best regards,

Ahren
CNCRouterParts (http://www.cncrouterparts.com)

TerribleDamage
08-11-2014, 12:43 AM
Hey all. I encountered a bit of a snag assembling the Y axis. Like the website suggested for the steel rails, I used the z-axis motor mount as a spacer and meticulously straightened the rail. Now, those 5 aluminum supports/whatever that fit in between the rails is a hair too big. I can't slide any of them between the rails. I see three options, but I don't know what is best:

1) Forget those 5 pieces of metal ever existed
2) File down one side of each piece so it'll fit between the rails
3) Undo one of the steel rails and use those aluminum pieces as a spacer

I'm also having a problem with the gantry risers. I can't seem to make all 6 bearings rotate at the same time for either riser. Individually, each bearing block is fine. But when tightening them to the gantry risers, not all the horizontal bearings rotate at the same time. On a scale of 1 to 10, how important is it that all 6 bearings make contact? The risers don't seem to have any play at all, so that's good. Would it be difficult to adjust those linear slides once the Y axis gantry is installed?

Also, on of the risers runs smoothly until the last 2 inches, then grinds to a halt. Does this mean the steel axis isn't straight enough? It would be a serious challenge to make it straighter than I already have.
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BuckNaked31
08-11-2014, 12:48 AM
Those pieces are to align the rails, you just bolt them up and go...

Sent from my LGMS769 using Tapatalk 2

ahren
08-11-2014, 12:56 AM
Terrible,

On your gantry, I'd choose option 3 and loosen the bottom rail so you can install the rail clamps. These provide additional pressure holding the rail down, and also serve to keep things in place a bit better if you ever crash your machine so you don't need to re-adjust your rails. The top rail should now be straight and well positioned for the rack and pinion drive spacing.

On the gantry risers, on your scale of 1 to 10 for keeping all 6 bearings rotating, it's about a 2 :) The system by design is a bit "overconstrained by having 4 carriages, so it can be difficult to get every bearing in contact at the same time, but this is not really important. You can loosen the bolts that hold the carriages to the gantry riser after the gantry is on later if you want to adjust them, but it's probably not worth doing until you break the machine in a little.

On the riser that is stalling out, this is probably not a straightness issue, and is likely just due to a localized high spot on the rail. I would loosen your vertical bearings slightly on this unit, and again re-tighten after you have cycled the machine back and forth a bit.

We've had these discussions with other customers before, so we'll update our tips and tricks document with some of this information this week as well.

Best regards,

Ahren
CNCRouterParts (http://www.cncrouterparts.com)

TerribleDamage
08-13-2014, 03:05 AM
Alright, I re-did the y axis rail and inserted those pieces of metal. I had trouble at first with some rough spots when test rolling the high z plate. Dial caliper showed there were some places almost 20 thousands off! I was able to pull the max deviation to +4, -2. Rolling the high z plate is much smoother now, but for most of the rail, there is a hair of play if I put my hand under and push upwards. I'm going to continue the build, since getting a tighter tolerance on those rails will be very difficult. I put all my strength into my clamps to bend those rails into place.

Quick question. For the high z plate, those bolt are not accessible by a wrench. I'm guessing a 3/8" socket wrench is the required tool...but is there clearance for that? I'd hate to go out and buy one, only to realize later that it doesn't fit.

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Dan911
08-13-2014, 07:46 AM
I never purchased a kit but installed the set-up. I purchased/used socket head bolts for that. You would than just need and allen key.

ahren
08-13-2014, 09:54 AM
Terrible,

The hex bolts are intended to be installed with a socket wrench. I believe the proper size socket is a 9/16. In terms of clearance there should be plenty for this size socket. If you don't have a set of socket wrenches, you probably should anyway -- they're pretty handy for lots of things besides CNC :)

Best regards,

Ahren
CNCRouterParts (http://www.cncrouterparts.com)

TerribleDamage
08-18-2014, 12:36 AM
Hey all. I've had the z-axis finished (minus the spindle mount) for a few days. With the machine almost finished, I decided to take a break building it, and instead setup the electronics portion. I'd hate to finish the machine and not have the ability to drive it! There was no way I would pay for the finished, ready to cut NEMA 34 system from the website. The premium vs. the expense of the raw components is way too high. I considered the control box, but even that seemed expensive. Here's what I did:

I picked up an Antec computer case and molex connectors from an electronics store, a 12" x 16" polycarbonate sheet from TAP plastics, and 4 heatsinks from a used electronics warehouse. There were a couple things I noticed. On 3 out of the 4 gecko drives, at least 1 of the screws on the back was not properly countersunk. This made it impossible to properly mount the back of the gecko drives flush to the heatsinks, so I had to do it with the bad screws mounted just off the side of the heatsink. On one gecko drive, both screws were not countersunk, so I used a dremel to grind one of them back. I know it's from a different company, but it should be fixed.

Anway, hooking up the pmdx and smoothstepper worked first time. I tested one of the drivers with one motor, with the other 3 geckos disabled...the motor turned first time, no problems. My wiring convention is simple. If a wire is white, it is a wire. If a wire is green, it is a bigger wire.

Quick question...for the cable chain carriers, what is the minimum size I can get away with for X and Y axis? I'm looking to buy some cheap chinese chains from ebay/amazon/alibaba/whatever. But I don't know the best size to get.

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Frankmali17
08-18-2014, 10:23 PM
Hello Ahren, CNCrouterparts, and Terrible.

I know that you guys offer enclosures for the electronics, but everything adds up quickly....
Is there any particular performance problem with using PC cases... some come with basic 12v and 5v power supplies and cooling fans... as far as keeping dust out, that can be even taped off selectively.... I would appreciate any experienced insight.

ahren
08-18-2014, 11:30 PM
Frank,

As long as you do a good job making reliable connections to the various components, there shouldn't be any impact at all on performance from using a PC case -- this is a resourceful and cost-effective option for a lot of people. We do have a lot of customers who like the pluggable connectors and more industrial setup our metal Nema enclosures offer, and it can be a struggle to fit everything nicely and wire it all cleanly in some smaller PC cases. However, we'd certainly encourage anyone who wants to try their hand at wiring a panel and doesn't mind the aesthetic trade-offs of using a PC case to go this route.

Best regards,

Ahren
CNCRouterParts (http://www.cncrouterparts.com)

TerribleDamage
08-19-2014, 02:14 AM
I think a PC case will be just fine. I was thinking about using the CNC machine to make a nice interface panel, should be pretty simple.

Question: For the NEMA34 rack and pinion drives am I supposed to uninstall the lower ball bearing to I can screw in the tensioner? I consulted the 3d model, but it looks like it's using a different type of tensioner. From the picture on your website, I can't tell if the ball bearing is still there or not. I also have a few extra parts, so I'm not sure if I'm doing something obviously wrong.

Also...I just read on the website that this thing gets 1273.2 steps per inch...but that includes 10x microstepping. If I'm cutting wood with small features (1/8")...are all my parts going to come out with a washboard-like finish?

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nlancaster
08-19-2014, 02:57 AM
Terrible, in the package for the tensioner is a long screw used for the upper stationary bearing on that carriage. I had to pull my bearing carriage off because I forgot about putting it in.

Here see my picture of my completed tensioner install.

http://www.pdxmc.com/uploads/CRP4848/rack1.jpg

ahren
08-19-2014, 10:16 AM
Since you already have your carriage installed, you can loosen the bolts holding it to the gantry riser and rotate the carriage out to replace the bolt. You should not need to re-adjust the carriage bearings since the bearing bolt you are replacing is one of the concentric (non-adjusting) bearings. When you've completed it, you should be able to rotate the carriage back into place.

The resolution on the standard rack and pinion drives is not as high as the PRO drives, but still yields nice detail in smaller work. If you decide you want to go to a higher reduction later on, it is possible to use a PRO spindle and larger belt with the standard rack and pinion drives, but we have many customers using the standard Nema 34 drives for intricate work.

Best regards,

Ahren
CNCRouterParts (http://www.cncrouterparts.com)

TerribleDamage
08-19-2014, 01:42 PM
Alright, I'll try that tonight. It's confusing, because the 3d models don't match for the gantry riser assembly, y axis assembly, and the fully assembled machine model. And from the picture on your website, it appears the carriage is upside down. Not only upside down, but attached to the bearing closest to where the rack and pinion would be.

Thanks Lancaster. I'll try to connect mine exactly like yours.

As for the resolution...oh man, counting half-steps, it's only 255 steps per inch... 0.0039" per half step. That's huge. I've never used a microstepper before, but my understanding is that it's more for smoothing the motion, not so much for added resolution. The 0.002 repeatability spec seems like a stretch. I will measure the performance with a dial indicator when the machine is finished...definitely some time this week.

ahren
08-19-2014, 02:55 PM
Terrible,

You're right. I just checked the picture on our website for the Standard Nema 34 drive and the carriage is shown upside down -- aye carumba. We'll get that corrected right away, and I'm sorry this threw you off -- I'm surprised this hasn't come up earlier.

Ahren
CNCRouterParts (http://www.cncrouterparts.com)

Frankmali17
08-19-2014, 02:57 PM
Hey Terrible...
You seem quite pessimistic about all this...
I hope it all works out better then you expect.
Please document your test with the dial indicator well for us... pictures would be great.
Also consider one thing.... A rack and pinion machine gives good performance over long travel... where a screw or other drive would whip around too much...
More importantly, the more you increase the gearing for higher precision, the slower the system becomes... This is more of a CNC router, and a small milling machine for metal... I don't think you can measure 0.0039" in woodworking very well, and certainly no one is producing furniture or cabinets to those tolerances.

TerribleDamage
08-19-2014, 03:18 PM
Hehe, I'm a pretty pessimistic person in general. I'm definitely aware of the rack and pinion vs. screw tradeoff. I wanted speed (I may use it for a pick and place machine later) and size, so I chose rack and pinion for that reason. I just thought it would be geared down a little more. I am planning on using the machine to cut wooden gears for clocks and things like that, and sanding between teeth of gears is really difficult and time consuming, so if I can get a nice smooth finish, that would be awesome. But for escapement wheels, some of my features can go down to 0.02 inches. Maybe I just need to make bigger escapement wheels. Anyway, hopefully I can make my first cut by monday!

CYoung
08-19-2014, 03:57 PM
Sounds like you need a co2 laser to cut those small gears.

TerribleDamage
08-19-2014, 04:13 PM
I considered that, but then all the edges are burned and wouldn't look nice. And to sand all that burned wood off would take a long time. I tried cutting on a 4x8 foot shopbot alpha, and it did a bad job. But I tried the same part (exact same toolpath, rpm, feed rate) on a shopbot buddy alpha, and it did a much better job. Maybe feed rate was too high for 4x8 foot shopbot? One problem I got is that the wood chips easily, so I may try milling brass sheets for small gears and wood for larger gears. I'm hoping that, now that I have a router in my garage, I can spend all the time I need to set it up properly and experiment with feed rates, tool paths, etc. Instead of being limited to a 4 hour block at a shopbot. More time to try things out should mean better cuts.

CYoung
08-19-2014, 04:22 PM
What material and thickness are your small gears?

TerribleDamage
08-19-2014, 04:26 PM
Usually one of these...I spend time at the store trying to pick out the best quality sheets :)

1/8" finnish birch plywood from woodcraft
1/4" baltic birch plywood from woodcraft

CYoung
08-19-2014, 04:44 PM
Ive been playing around lately with an Epilog Helix 60W and it could cut those thicknesses/material very easily and with excellent precision. But you are correct about the burnt edges, I don't think there is a good way around that, unless you use tape on the cut lines. But then you have to peel off all the tape which is a pain.

Frankmali17
08-19-2014, 08:41 PM
Sometimes smaller machines or mills are better for tiny parts.... sanding off the burnt stuff from a laser would then change the size of the part, besides a lot of labor... for cut quality, you have to experiment sometimes quite a bit, until you reach the desired/tuned in results...
You may want to do some rough passes, and then final cuts taking off a very fine amount...
Good Luck.

- - - Updated - - -

Post more pictures of your progress :)

TerribleDamage
08-20-2014, 02:24 AM
Yeah, I was considering buying a much more accurate but smaller machine, but I knew that as soon as I bought it I'd think of a project that requires a larger footprint! I think 48x48 will be sufficient for years to come. I've seen people go very small with laser cutter and plastic (like, 100 teeth on a gear the size of your pinkie), those things are impressive.

Anyway, aside from my world class cable management scheme, my machine is F-I-N-S-H-E-D! Done. I hooked it up to mach3 and gave it a spin, smooth as butter, sounds great. For now, I have geckos limited to 3.8 amps since I don't have the fans in my pc case hooked up yet. I was able to get some measurements on the X axis with my dial indicator. The microstepping does a better job than I was expecting. The max error was 1.2 thousands. The jumps in the mach3 readout are just due to aliasing, since I was increasing by 1 thousandth at a time, so sometimes it was skip and do 2 pulses. I also accidentally measured backlash. I wasn't paying too much attention, but it was between 4 and 8 thousands. I'll recheck later.
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TerribleDamage
08-21-2014, 03:26 AM
Quick question...I ran my first toolpath (aircut)...60ipm, a simple square, spiral-fashioned pocket. The machine was vibrating terribly, making all sorts of terrible noises. I tried again at 120ipm, it was much better. At 240ipm, it sounded good. I tried very low feed rates too, 6ipm, and it sounded as bad as 60ipm. To change the feed rate, I simply edit the g-code and change a number after F early on in the file. I changed my steppers from 3.8amps to the max 7amp limit, but the problem is still there. Would could be causing that? It happens for both the X and Y axis. Just putting my hand on the machine, I could feel it vibrating a lot at slow speeds. I'm using the xml config file for crp4848 standard, I haven't fooled around with any settings. Thanks!

Frankmali17
08-21-2014, 12:22 PM
I'm not the most experienced here but I think it sounds like some "Constant Velocity" settings.... I know that I ran into problems like that while V Carving, Basically it's like the machine moves and stops at every point... so while traveling to a certain destination.. there may be many points along the way....
Think of it like a GPS coordinate system....

Maybe Ahren can lead both of us a little on setting CV...
Let us know if that helped.

ger21
08-21-2014, 12:25 PM
If you have Gecko drives, have you adjusted the trim pots?

Frankmali17
08-21-2014, 12:26 PM
Also, what did you think of those steel legs? I am working on designing a bigger footprint 5x9ft PRO machine... I intend to work with CNCRP guys once I figure out how I want it... I'm going to request heavier extrusion...
So I was thinking of getting additional extrusion for the legs, and building cabinets underneath as well as plywood skins to make it ridgid and not sway as the machine moves.... Do you thinks this steel leg kit works well/ puts together well/ how are the bottom feet?

THank you

ahren
08-21-2014, 01:30 PM
It is worth checking to make sure that your post-processor is outputting actual arcs -- some CAM software breaks arcs into tiny line segments. At higher speeds, the Mach CV settings actually smooth this out, but at lower speeds the machine will actually start and stop at the end of each line segment. I would check your g-code to make sure actual arcs are being output.

Best regards,

Ahren

TerribleDamage
08-21-2014, 03:03 PM
The toolpath is a straight edge square spiraling outwards, so each move command takes several seconds to complete, and is a straight line. I will try ger21's suggestion...I have forgotten to adjust the trim pots on the geckos! I just read they're supposed to be adjusted at 2 revs/s, and since it's 1.5708 in / rev, I'll tune it at 188ipm. At that speed, the machine sounds okay already, but hopefully if I tune them, it'll solve the problem at lower speeds.

Frank, I have mixed feelings about the steel leg kit. On one hand, it was cheaper than me buying a decent miter saw and wood to build my own table, so that was the primary motivation for me buying the leg kit. The steel is heavy duty, no chance any of those beams will bend. But there are two main problems. First, (at least for the 4x4 foot router legs), for each side, there is only one horizontal (or diagonal) beam, not two. It can stand up on it's own if you tighten the bolts down hard, but it can never be sturdy on it's own. It really relies on the base of the machine to be fully defined and rigid.

Also, at first, I made the mistaken assumption that the steel beams should be flush. I spend hours squaring everything, making sure it was perfectly vertical for each leg, making sure they were just the right height for each leg, (my garage floor is not level) etc. But it turned out that making the steel beams flush caused the width of the legs to be inches too narrow to mount the base of the machine. Ouch, all that work for nothing. Also, at the top of each leg, there is a metal thing to connect the leg to the aluminum extrusion...but that is held onto the steel leg by a single bolt. So at the end of the day, my entire machine is resting on 4 lonely bolts. I'm definitely going to add a second bolt for each leg.

Also, at first, I assembled my base on the legs...it was frustrating and time consuming constructing up in the air like that. And when it was done, it wasn't perfectly square. I ended up taking the aluminum down, assembling it on a level floor carefully with a precision square, clamps, etc. Then I put that onto the steel legs. It was a serious challenge for me to lift and mount the 4x4 base and mount it myself...with 5x9 footprint, you will need friends to help. Anyway, that's my whole spiel about the legs. At the end of the day, they do work. But if I ever wanted to add shelving, I'd have to add another beam, since the two horizontal beams are not at the same height. I haven't run my machine over 300ipm yet, so I don't know how well they hold up with big forces yet.

TerribleDamage
08-25-2014, 08:21 PM
Seems tuning the geckos was the problem. Had to tune them at around 25 -> 50 ipm, but now the machine sounds and feels much better at slower speeds. Getting ready to use loctite on the set screws and square the Y gantry tonight.

Quick question...I see most people use two layers of MDF on base of the table. What is the best way to secure that MDF to the table? Do they bolt it to the aluminum extrusion somehow? Also, do most people face the top of the MDF, or just leave it as is? I'd like to avoid a toxic dust cloud in the garage if I can. Thanks!

ahren
08-25-2014, 08:44 PM
Terrible,

It's helpful to mount one piece of MDF to the extrusion more or less permanently, and then have a sacrificial board fastened to this that you can plane flat to the machine, and then discard if it gets too beat up. We use a Raptor composite nailer on our demo machines here (it's nice since you can machine through the nails), but you can also use recessed drywall screws to hold the two sheets together. You will want to come up with some sort of dust collection system at some point regardless.

To mount the bottom sheet to the extrusion, there are lots of ways to do this, but we find t-studs or t-nuts are the easiest. We sell these in our fasteners section here:

Fasteners and Brackets | CNCRouterParts (http://www.cncrouterparts.com/fasteners-and-brackets-c-43_36.html)

When it comes to squaring your gantry, while you can do this mechanically, I'd suggest getting some sort of switches so you can un-slave the axes and auto-square when you home. You don't have to get ours, but this feature is just really useful and Mach and the newest Smoothstepper plugin (which I believe is V10r2d1d) support it very well.

Best regards,

Ahren
CNCRouterParts (http://www.cncrouterparts.com)

TerribleDamage
08-25-2014, 09:27 PM
Alright, I may place an order for some brackets and bolts tonight.

I'm installing my home/limit/emergency switches tonight. I forgot to use clamps when installing the gantry risers, so I think my unsquareness is beyond what can be done with software. The left side (x-) only gets half an inch close to the bumper before the right gantry hits. Is the CRP4848 standard xml config file un-slaved by default? Or will I have to play around in mach3 settings to figure that all out?

ahren
08-25-2014, 10:39 PM
Terrible,

In that case, your best bet may be to place a small shim on the inside edge (only) of the gantry riser, between the riser and the gantry extrusion, on the side that is furthest off the back bumper. This effectively "levers" the gantry forward by the ratio of the width of the riser to the length of the gantry (about a 25:1 ratio, so a 1/2" delta should take about a 0.020" shim). The R&P units can take out quite a bit of skew if you auto-square, so it doesn't need to be mechanically perfect.

The XML file we provide on our site has the X and A slaved by default, but if you set up homing with both an X and an A home switch, they will un-slave automatically during homing. You are welcome to give us a call tomorrow if you'd like help with any of this.

Ahren
CNCRouterParts (http://www.cncrouterparts.com)

TerribleDamage
08-27-2014, 01:47 PM
I've got it pretty square. Just in case others read this thread, the brackets for sale on your side are for the metric extrusions for the PRO machines, not standard machines. I ordered them, but soon got a phone call warning me that they'd be 1mm proud for the standard CNC machines which use fractional instead of metric like the pros. That's no good. Instead of brackets and screwing in the bed from below the table, I have another plan. I will use the CNC machine to drill holes in my bed, (1/2 MDF, screwed on top of 3/4 MDF....no way I'm going to unscrew them now), so I'll be able to drop the t-nuts right through the bed into the aluminum extrusion, and use a hex flange nut to secure it. It'll be a shame the table will have a bunch of holes in it, but I'll get over it, I'm sure.

BuckNaked31
08-27-2014, 02:49 PM
Faztek has those brackets and you can order them online.

Sent from my LGMS769 using Tapatalk 2

TerribleDamage
08-27-2014, 03:02 PM
Yup, I was able to locate them on apex industrial supply yesterday also. But for those prices, I think I'd rather have some cosmetic holes through the MDF bed, and not have any brackets.

BuckNaked31
08-27-2014, 03:40 PM
You'll be better off that way. I have one layer of plywood, then 2 layers of MDF on mine. Since my frame is made of welded steel tube, I just bolted the bottom layer of plywood to it and screwed the MDF layer and glued and screwed the top layer. I also have 5/16-18 square nuts, 72 of them, embedded (72 pockets with an 1/8" cutter, took about half an hour) in the first MDF layer, then I have 3/8" holes cut down to the nuts. I can clamp or index in these holes. They will also accept a 3/8" shoulder bolt since the threads are 5/16... I also have a pocket cut in the corner that accepts a 123 block lined up to the matrix of holes. I use my 123 block as a touch plate, so it's wired to the probe input. Once you have your scripts written, you can located to edges and bolt holes quickly. Anyway, this gives me plenty of thickness on the top board for leveling it later after I screw it up. I've only replaced it twice in 6 or 7 years. I've been thinking of engraving a ruler into the edge just for convenience :)

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CYoung
09-01-2014, 12:47 AM
Bucknaked
Can you send some pics of your table? It sounds very interesting. I am trying to figure out how to build out my table and yours sounds perfect.

BuckNaked31
09-01-2014, 03:41 AM
Sure, I'll snap a couple tomorrow...

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nlancaster
09-01-2014, 04:30 AM
I actually Tapped the Aluminum extrusion 1/4-20 to hold the base of the table down 18mm baltic birch fills the entire table side to side, front to back. And I am then going to insert 290 1/4-20 Thread inserts from the bottom of that. then 1 layer of 3/4 MDF on top for a spoil board. I will then pocket the spoolboard 1/2inch diameter down to the baltic birch after surfacing. So that I can use 1/2inch pins to align parts on the table.

BuckNaked31
09-01-2014, 06:07 AM
I use the inserts for individual tooling plates that I attach to my spoil board. I found that MDF dimples really bad when I use them, and they are expensive as all get out when you need a boatload of them. 100 of the square nuts was $7 :) Also, the 5/16 size is compatible with all my rockler clamps and bolts. Shoulder bolts with 5/16 threads are 3/8" at the shoulder, which is also a standard shank size for router collets and I could do most of the drilling with a stub length 3/8" drill bit (I don't have an ER type collet, I'm on a PC router with the precise bits collets)

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TerribleDamage
09-01-2014, 07:40 PM
Man, now I'm worried I'm underbuilding my bed! I just used 3/4" MDF under 1/2" MDF, and secured the two together with 48 brass screws. It seems pretty solid, and when I do cut wood, I'll use a sacrificial board and secure it to the table with brass screws. Later, I plan to secure the MDF to the aluminum extrusion using 32 t-bolts...hopefully that will be enough. I read things like 290, that's like 9x as much!

On a positive note, I have drag chains installed, and all the limit/home switches wired and tested...securing the bed and confirming the machine cuts square are the last two items on my checklist.

248030

BuckNaked31
09-01-2014, 08:55 PM
You're probably OK, it depends on how you use your machine. Almost everything I cut is double sided, so all my holes are for indexing, I try to clamp in the same holes when I can so there are lots. I only have a 30" x 54" cutting area. I'm not cutting sheet goods like you guys are.

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BuckNaked31
09-04-2014, 02:20 AM
Ok, here's some pics with the screenshots from my cad files, I didn't take any pics putting it together. I think you'll get the gist of it. It works very well and didn't cost squat. I don't locate with home switches, I locate with a 123 block wired to the computer. I also made my own Mach screen that has everything I need in normal operation on the main screen done in some colors that are pleasing to my eyes. This includes circle finding and edge finding scripts and autozero for the Z.
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TerribleDamage
09-05-2014, 09:26 PM
I get using a 123 block for z-plate...but it might be less risky to get one without holes. Just a thought.

BuckNaked31
09-06-2014, 03:40 AM
Well, the ones with the holes are cheaper! If I can't line up the cutter without hitting a hole, I'd better give up on this whole woodworking thing :)

TerribleDamage
09-22-2014, 02:39 PM
Hey all. So, I've gotten past simple profiling and facing operations, and I was doing a piece over the weekend to engrave some small text with a v-carve bit. At a feed rate of 70 ipm, the gantry moves back and forth very quickly, with small movements. But when I did an aircut pass, I could help but notice the entire table was shaking very badly. I had to slow the rate to 10ipm just to get an acceptable cut. In short, the legs do not seem to be even remotely adequate for making rapid, small cuts. That is very disappointing. It was quite a cost to get NEMA34 over NEMA23, but I can't take advantage of that power because the table just isn't stable for rapid cuts. What is the best way to reinforce the legs? Will 2x4 lumber be sufficient? There must be a way to fix this...Thanks!

ahren
09-22-2014, 03:42 PM
Terrible,

To reduce vibration, your best bets will be to:

1) Add mass to the base of the machine. Other users have used bags of sand. In our own shop, we've used boxes of bolts on a shelf we built at the bottom.
2) If you want to stiffen the leg frame, you can add a shear panel to the outside of the legs bolted through the holes at multiple locations. 3/4" plywood is probably your best bet, but even 1/2" could work. Sort of the way OSB/plywood stiffens up the walls of a house, adding shear panels can add a great deal of extra rigidity.

That being said, some of the shaking may look worse than it actually is. We've done some testing where we mounted a camera on the moving head of the machine, and while the base was shaking considerably, the video of the actual cuts barely showed any vibration. We were quite surprised how much the actual machine frame isolates motion at the cutter, but at the level of detail you are looking for in your parts even small vibrations may still cause issues.

If you're still having trouble, feel free to give us a call and we can look into some other things as well.

Best regards,

Ahren
CNCRouterParts (http://www.cncrouterparts.com)