My third build, all steel this time!

[Fluxion]

I am already in the process of building my third CNC router. I have a frame and gantry built of welded steel tubing that was designed around SBR20 fully supported round rails but after starting this thread http://www.cnczone.com/forums/linear...38786-cnc.html I have switched to Hiwin 20mm rails. My frame is built out of 4"x8"x0.25" wall rectangular tubing with 2" square legs and bracing, it's stout and weighs about 800 pounds right now. The Gantry is made of 8" square 0.25" wall tubing and weighs in at about 180 pounds right now but I haven't added the Z axis yet. The z axis will be built around the Hiwin rails and a 2010 ballscrew. I have purchased 3 NEMA 34 pro rack and pinion drives from CNCRouterparts.com, one for the Y axis and two for the X axis.

It has taken me awhile to save up some money but now I am ready to get this thing up and running. Below is a list of things I am planning on ordering very soon, I would order tonight if I was 100% sure. I would love it if you guys who know about this stuff to chime in and give your opinion.

1 Ethernet Smooth Stepper
1 PMDX-126 breakout board
1 PMDX-107 speed control
4 Gecko drives- Can't decide here. I was leaning towards the G201x or the G203v
Power supply- 72 volt 20 amp from Automationtechnologiesinc.com
4 Steppers. I was thinking of the NEMA 34 960oz from CNCrouterparts.com or the 906 oz from Automationtechnologiesinc.com
2.2KW Chinese spindle
2.2KW VFD for spindle, I'm thinking Hitachi WJ200 but may have to go with one from Huanyang. Is a 2.2kw VFD appropriate for the 2.2KW spindle or do I need a larger one?

I really need help selecting the steppers and matching the correct power supply, I don't fully understand how to do all those calculations. I would like fast rapids,1000 IPM would be nice as this will be used for 3d carving.

Ok, now for some pics!



My revised 2D drawings.

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Pics from pouring the Epoxy bedding.

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Here is a few pics when mounting the rails.

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This one shows a phenolic template I cut at work on an Onsrud CNC router to align the linear trucks.

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Aligning the Y axis linear rails.

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Starting the mock-up of the E-Chain.

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I need to get some current pics, I have progressed a little bit since these were taken. I'll get those and update the thread soon.

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[pippin88]

Looks like a great machine.

How thick are your epoxy areas? I used epoxy on my machine (In progress) but it didn't level well on some areas, I think because I didn't do a thick enough pour.

I'm moving to Leadshine digital drivers (paired with a mesanet hardware step generator) from a G540 because they are so much quieter and much less heating. They are quite well priced, so consider them. Some models have pretty advanced features such as sensorless stall detection.

[Fluxion]

Hi pippin88, I'll have to look into those Leadshine drivers, I just don't know much about them. My epoxy pour was at least a 1/4", a little thicker in spots. That was the minimum recommended when I purchased the epoxy. Btw, in case anybody is interested I did use the black machine bedding epoxy from precisionepoxy.com It's kind of expensive but it flowed out real nice and looked like a black mirror. I used a scraper to cut the meniscus flat and that kind of scraped up the epoxy at bit.

[bgolash]

Hi
I think the build is going great. Your gantry is going to be very heavy. I would use servos instead of steppers. I`ve seen alot of builds and they end up
switching to servos. Servos have their own problems but when I switched I ended up with a faster and more dependable machine.

[Fluxion]

Hmm. Servos, When I started this project I wanted to go with servos but I was thinking servos would be out of my price range. I just did a little math and I am a little surprised.


If I were to place the following 3 orders like I had planned when this whole project started:

CNCrouterparts.com
4- 960 oz in stepper motors $476
4-Gecko 201x drivers $468
1- Ethernet Smooth Stepper $200
Shipping $50.27
Total $1194.27

PMDX.com
1-PMDX-126 Breakout board $174
1-PMDX-107 isolated speed control $57
2-PMDX-HDR26 ribbon cables $10
Shipping $8
Total $249

automationtechnologiesinc.com
72v/20a powersupply $199
Shipping $11.39
Total $210.39

This would give me a grand total of $1653.66

I can order the 4 axis 1150oz in dc servo kit from automationtechnologiesinc.com for $1,556.94 including shipping. Wow, I am pleasantly surprised. I would have to upgrade the C10 breakout board to the C11 to get the spindle control but that shouldn't be more than another $100. so that makes both systems very close in price at $1656.94, provided that servo kit would do the job. What would you guys do?

I was planning on building a new computer with a mATX motherboard just for this new router and I would have to add in a parallel port for this servo system. I was thinking of saving $300 and using an older IBM ThinkCenter with a Pentium 4 running XP pro, It has a parallel port.

[ger21]

Why do you need a parallel port for the servos?
Were you going to use the Smoothstepper with steppers, but the parallel port with servos???

[Fluxion]

Why do you need a parallel port for the servos?
Were you going to use the Smoothstepper with steppers, but the parallel port with servos???

Hi Gerry, I guess I didn't explain myself very well, sorry. Yes I was planning on running the ESS with steppers but while playing with the prices of the various components I left it out to get the price of the servo system closer to the stepper system. I guess I don't know for sure but I was assuming I could still use the ESS with the servo drives. When I mentioned the older computer I was thinking I could save a little money right now with the computer side of things and get this up and running a little sooner. While I don't have a budget set for this router, I don't have a whole lot in my toy fund right now.

[steve123]

I like your epoxy work a lot. I plan to do something similar.
I hope you are planning on closing off the ends of the gantry beam, or it will parallelogram on you.
Nice work!

[pippin88]

I don't understand why people pay so much for a breakout board (PMDX-126), especially given it doesn't have spindle control output.

[Fluxion]

After looking around I agree. I am considering the C11 now. I still don't know what size motors to go with. I like the idea of using servos if they would work with my rack and pinion belt drives I already have. I was planning on direct drive for the z axis ballscrew.

[Fluxion]

I like your epoxy work a lot. I plan to do something similar.
I hope you are planning on closing off the ends of the gantry beam, or it will parallelogram on you.
Nice work!

Thanks Steve! The epoxy forming was fun, I wish I had taken more photos during the process. I wasn't planning on closing off the gantry ends initially. After putting a dial indicator on the temporary Y axis carriage I have discovered that I can deflect the 1/4" thick gantry tube just by squeezing the end. The only problem now is the epoxy beds have been poured on the tube and welding might cause delamination, not to mention deformation of the tube itself. I had thought about bonding a full length diagonal brace inside the tube, maybe something like 14ga or even 11ga sheet. I wonder if I should have closed the ends of the main tubes of the table? The reason I left them open is that the Onsrud router at work has uncapped ends on the gantry and table tubes, granted they are thicker but they are also quite a bit larger. The table is built out of 8"x14"x3/8"wall and the Gantry is 12" square with a 3/8" wall. I am open to suggestions here.

It has taken me a year to get this far and I have some cash burning a hole in my pocket and I want to order motors and drives among other things so I can move forward. I don't really have a deadline but I do have some carvings to make for a job that will be paying for most of this router. I have done tons of reading on motor selection and have confused myself so that is why I am asking for help.Does anybody have anymore input as to what would be best for my router? I am leaning towards servos now but I am unsure of what to buy to be compatible with the 3.2:1 rack and pinion drives I have. I was thinking of buying the biggest servo package from AutomaionTechnologies.com, would there be any problems tuning the drives if the motors are too big? Is having too much torque in a servo really a problem? I just might have to give Automation Technologies and Gecko a call and see if they can offer any advise.

[pippin88]

That tube should not deflect with hand pressure. Can you post a photo of your testing setup?

[Fluxion]

That tube should not deflect with hand pressure. Can you post a photo of your testing setup?

Sorry, I didn't take a pic. I'll try and explain what I did. I had the gantry laying on its back with the y axis rails and the temporary y axis carriage facing up, in this position the x axis mounting pads are perpendicular to the floor. I had my 6 foot level clamped to the gantry end pads as a straight edge ( its all I had that was long enough). I was using the dial indicator on the temporary y axis carriage ( as shown in picture # 6 in my first post) to align the y axis linear rails. After the all bolts of both rails were tight and the alignment was as close as I could get, I had the temporary y axis carriage at one end of the gantry tub and for some reason I tried squeezing the end of the tube. I was shocked when the dial indicator did move. I could only do this at the very ends of the y axis, move the carriage in 2" and I couldn't get any movement.

[kimosawboy]

Your build looks really great!!!
Me being one of the ''Newbies'' on here, I have scoured many, many designs on this forum and I have to say that yours catches my eye in a lot of good ways. Your design is straight forward and relatively simple (although I'm sure you put many hours into it) and looks plenty strong. I'm surprised nobody has commented on the lack of diagonal bracing in the front and rear as it seems most people go overboard on welded steel applications.
The use of epoxy is great, I dont understand while more people use it. I do want to ask if you had any bubbles with the epoxy you used, if so did a little heat take care of them??
Looking forward to updates on this..
G. Vavra

[dfaszer]

designed around SBR20 fully supported round rails but after starting this thread Round VS Profiled rails I have switched to Hiwin 20mm rails

I read the post, but no one said why the profile rails were better than the round. Could you explain why you chose them over the round?

Other than the length, is it more advantageous to go with a rack and pinion over ACME screws?

Thanks,

[ger21]

I read the post, but no one said why the profile rails were better than the round. Could you explain why you chose them over the round?

Profile rails are stronger, and far more rigid than round shafts and bearings.
Round shafts and bearings can often have some play in them, especially the open ones.

[klaas123]

Profile vs round rail explained

[Fluxion]

Kimosawboy, I didn't even see one bubble five minutes after pouring the epoxy. The stuff I used flowed out and looked like a black mirror in a few minutes and looked the same after a few days. The stuff is amazing. I have since scraped it up a bit and lightly sanded with 60micron film but it did look like glass. I made the pour, fixed a couple leaks with caulking and went for lunch. I came back about an hour later, it had started to gel and no more leakage so I locked up the shop and checked on it the next day, I didn't want to stir up any dust.

dfaszer, I chose the profiled rails mainly after many suggestions in my "http://www.cnczone.com/forums/linear-and-rotary-motion/238786-cnc.html]Round VS Profiled rails" thread and playing with the numbers in an excel spreadsheet that dmalicky (I think) created called "RailSpacingStiffness-1.xls". I don't have a link handy and its late but if you can't find it I will look it up. The difference between the SBR rails and the profiled is dramatic. I did get a good price on Hiwins straight from China, I bought from solar.jean through ebay. After having these rails and playing around with a 20mm SBR that a friend had, I am sure I made the right choice even though they cost a little over twice the price. Hell, they would have been worth it a four times the price.


I found the thread in which dmalicky posted the excel file I mentioned above. http://www.cnczone.com/forums/diy-cn...ml#post1408004 post #29

[Fluxion]

I set up a magnetic base on the Y axis carriage and a dial indicator touching the base of the gantry end. When I hold on to the gantry end (blue arrow) and push on the gantry tube (red arrow) I can easily get 0.002" deflection and I did get it to 0.05" with just hand pressure. cutting forces will certainly deflect the gantry at least this much.



Now to stiffen up the tube to keep it from parallelograming on me, would epoxying in a diagonal web or rods be sufficient? I think its too late to weld ends on the tube and I do remember dmalicky posting some ideas on this but he suggested welding them if I remember correctly. I'll go read the thread again I guess.

Here are a few more pics to show where I am at right now. I have been working on mounting my electronics enclosure and making cable trays. I have one end of the E-chain for the x and y axis mounted already and will be making brackets for the other ends soon. Sorry that the photos are hazy and all around crappy, I should be using my camera instead of my iphone.

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As you may have noticed I used genuine E-chain from Igus that is open, we had the closed kind fill up with sawdust at work and had to replace all the cable carriers with the open style. I purchased all the E-chain new from http://www.cableorganizer.com/ and surprisingly it wasn't much more than the used stuff on Ebay and I could get exactly what I wanted. I also cut large holes in the trays where the cable carrier will lay so that sawdust falls through and since I used such thin sheet metal I decided to flare the holes. The flares really did strengthen the trays, below are a couple of pics while forming the flares with home made tooling. I turned the punch side from maple and used a solid surface scrap for the die. Quick and easy, someday I will get proper flaring dies.

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[ger21]

I'd just epoxy in some plywood plates to stiffen up the tube. Before you do that, cut a snug fitting piece and press it into the end and redo your deflection test. But I would think it would be fine.

I priced out my echain from the same place, but haven't purchased it yet. Yes, it's much nicer when you can get exactly what you want.

Nice work on the tray.