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Deviant
08-25-2006, 09:34 AM
Hello All.

I'd like to get some opinions on the two mills. I've read alot on the forums and comment on my fair share. I'm currently in a position where I'm about to buy a new mill.

x3 Pros:
Mass
Z-travel

x3 Cons
Fit/Finish

Taig Pros:
Fit/Finish
CNC Ready

Taig Cons:
3/8 shank maximum
Lack of Mass

How does the x3 compare to the taig. The both appear to be similar machines. Albiet the x3 is alot bigger, the taig seems to be better made.

I currently have a x2 mini mill, but I have been very unimpressed by it so far. Although, I never completed the cnc conversion. Just the fit and finish, seemed lacked. Even after cleaning it up. Alot of pushing and pulling to get the table sliding smooth. Maybe I got a bad one.

How does the x3, compare to the x2 for fit and finish. Do the dovetails appear to run straight and true. Any warped tables?

How fast of cuts can I expect from the 2 mills? I have 250oz servos, I can reduce the speed for more power if I need. I'm mostly cutting aluminum, but I might do steel sometime. Is the x3 that much more suited for steel.

I really like the taig for being cnc ready and waiting. That is a big plus for me, as I've had the x2 for so long without any progress. Sadly, I like the x3 for the mass. I'm just concerned about the x3's overall condition. I expect the taig to be well made from everything I'd heard, but I don't want to be disappointed.

Anyway, just looking for some peace of mind before I jump into the purchase.

Thanks all... alot of money waiting to be spent.

dcprecision
08-25-2006, 12:28 PM
When I first began teaching myself the basics of PC based CNC machine building, I decided to build a servo driven TAG cnc mill. I am a professional tool manufacturer and own a both Bridgeport J head and a RF 45 mill as well as many other machines. My objective was to learn how to automate other processes of my manufacturing operation. After building the TAG and getting all the bugs worked out, I began making some small production parts in 6061 aluminum with it. The major problem with the TAG is lack of ridgidness and vibrations. When the machine is cutting, it produces a constant buzzing sound which is being caused by vibration. This sound translates into tool marks on the work. No matter what type of cutters and rpm combinations are used the vibrations are ever present. This does not mean that you cant do good work with it within its size scale, you must use extremely fine finish cuts at very low feed rate to get any resemblance of a good finish in aluminum. As far as steel and harder materials are concerned, they can be cut also but with finish penalties that are more pronounced than with aluminum. Also keep in mind that you always want to keep your material removal rate ( chip load and surface speed ) within accepted parameters. This can't be easily done with the TAG due to the above faults. The X2 will definitly offer more stability due to the cast iron construction and additional weight. I would also seriusly consider a belt drive conversion and eliminate the gear box. You get higher rpm and quiet operation. See attached photo of some parts made with the TAG.
ps. I sold the TAG afte 3 months of use for the reasons stated above.

Deviant
08-25-2006, 01:46 PM
I have a few projects that I'm looking at doing.

First, I want to make airsoft parts/guns. These would be very similar to milling out paintball bodies/bolts. Depending on the design and my skill/marketing.

Second, I've looked at making a few conversion kits for my wifes various hobbies.

And of course, I have alot of hobbies that would benefit from being able to make the random widget.

Now.
Almost everything will be out of aluminum. I don't forsee any steel or iron. But, I'd like to keep the option open. Never know what will happen.

What type of feedrate did you have to run your taig at, to get the proper finish. Can anyone post a video showing the feed rates of a taig making a good finish/roughing pass. And one on a x3? Are we talking like 2ipm or 10ipm? How does that really compare to what you can get on a x3. I've seen people talking about rapids at 270ipm etc. I think that is a bit obscene. Additionally, if I can zero my parts and design the right. I shouldn't have alot of rapids.

I've attached some pictures of parts like what I'm looking to make. Also, I'm going to be similar parts that require less mechanical parts.

Thanks

dcprecision
08-25-2006, 03:16 PM
Heyy guy,

These parts pictured look like die casts. You are not going to make anything like in your pictures with a TAG mill or possibly even with an x3. I think you should consider a machine in the range of a RF 45 as the minimum size with ball screws and 600 oz. servos. You are also going to need some sophisticated tooling, flood coolant and some type of interchangable tool setup such as the Royal quick change tool holding system $ 1000. look at it in the msc.com web site. This is serious machining work and takes a great deal of knowledge. So far as feeds as speeds on a TAG or any other mill go, general machining practice dictates a minimum surface speed of 300 ft/minute and a chip load of .0005 to .001 when cutting aluminum. So the formula pivots on the cutter diameter. So, if using a 1/4" end mill ( .785" circumfrence) the rpm needed is 4585 rpm. (5000 rpm) if it is a 4 flute, this gives 20,000 cuts per minute. At a chip load of .001, you need a 20 inch per minute feed rate. The feed rate formula is 300 x 12 / .785 x 4 / 1000. All of this is way beyond TAG capability. Machining centers cut this material with surface speeds of 1000+ feet per minute and feeds of over 100 ipm. When making small parts on the TAG you can get an ok finish with mist coolant when removing .005 of material at .050 deep at about 4000 rpm and 6-10 ipm but it is still buzzing. These TAG and similar mills are really garage and basement toys, but they do have production capabilities for small hole drilling and milling operations in soft material with up to 3 /16 end mills and at slow production rates.

Deviant
08-25-2006, 03:27 PM
hrm

Why do you say that these parts are out of the range of the taig's ability. The parts aren't actually very big. They are roughly 4x5x6x.5" or there abouts.

I would think that the taid would be perfect for that part. As for the tooling change. I wouldn't think I'd need to do much, at least for the outline. Ideally, you would change the tools for optima material removal. However, it was my understanding, that if you wanted to just set around all day. You could build the part with a 1/8" endmill vs a 3/4" rougher. I agree that it wouldn't be smart.

Those parts are cast for mass production purposes, but they are cheaply done. The performance sector of the sport is looking for parts with higher tolerances.

I plan on making some type of coolant system. Whether it's flood or mist.

I'm not trying to squeeze blood from a turnup. I'm just having a problem with that fact that your saying I can't make these part which is well within the working envelope of the taig.

Don't worry about the gears etc. Mainly looking at the clamshell platform that the parts plug into. That was mainly just an example of the type of work I'm looking at doing.

Deviant
08-25-2006, 03:36 PM
Just to add to the thread.

I do plan on milling out the bodies of the airsoft guns from stock. I understand that I'll have to make the fixture for hold the parts during each operation. And that I may even have to build them in parts and weld the complete parts back together, depending on the design requirements.

Thanks.

juzwuz
08-25-2006, 04:21 PM
Hi! Have you looked at

www.cartertools.com

There are a lot of links to various projects done with the Taig lathe and mill.

The following one looks interesting for paintball guns with a Taig mill.

www.whitewolfairsmithing.com


I just bought the CNC ready Taig 2019ER-CR from Nick Carter a couple of weeks ago. I'm just an average guy working in his garage with no access to heavy duty metal working machinery so for me the Taig mill should work fine for what I need. I only have an hour here and an hour there each week to work on setting up the mill because of the kids and a long "honeydo" list so I haven't actually used the mill yet. Putting the mill together (2 main pieces) and installing the stepper motors took just an hour (I'm slow). I'm currently working on the cnc electronics, software, computer, coolant system, etc.... The construction of the mill looks quite nice (though I don't really know how the x2 and x3 are...I've briefly played with them at Harbor Freight). Nick has been great in answering my questions and there is a lot of information on the yahoo taig forum. Hopefully I'll be up and running in a couple of weeks, and I can start making parts for my aluminum construction cnc router.

Deviant
08-25-2006, 04:29 PM
I've looked at both of those websites. I have sent Nick several emails for quotes. I asked him to check out what I'm looking to do with the mill.

I think that the mill should be able to do what I need, but I'm starting to question it.

Anyway, part of my other plan for the taig was to build a bridge type mill out of tooling aluminum plate with thk style rails. But that's long way off.

Just frustrated, I wish it was a little more cut and dry. It would make my decision alot easier. I tend to get conflicted reports. I don't want to be in a position where I get the mill running then realize that it's not able to do what I need it to do.

(grumbles)

juzwuz
08-25-2006, 07:28 PM
Yeah...I know about frustration. I've been gathering parts (a.k.a spending lots of money) for a cnc router but I still don't have a working machine. On the bright side, I have learned a lot about cnc parts (and their ebay prices) so I can usually tell when something is a good deal or not. For me, getting the CNC ready Taig lets me have a machine that is very close to being setup for CNC without spending too much money and time. If I ever get tired of the Taig mill I bet I could easily sell it on ebay for more than I put into it. Now...if only I could actually get the electronics set up, I could be making chips!

S_J_H
08-25-2006, 07:37 PM
I have a cnc'd x2 and if guys say it is more rigid than a Taig, I say forget the Taig for those parts.
I could see pocketing out those parts on my x2 but finish would not be all that great and it would take a while because feeds need to be pretty slow.

I also have a x3 which I am in the process of converting.
It is MUCH more powerful and rigid than my x2. The accuracy from the factory seems great. But of course if you convert it to cnc then how accurate it will be is up to you.
IMO the x3 is a great benchtop mill to convert to cnc.

Steve

phantomcow2
08-25-2006, 08:45 PM
The Taig is okay for small parts. Also, if you have patience. It may be the ideal machine for users who do a lot of this, especially with its high spindle RPM.
But in my opinion, the X3 is hands down the better machine. Or at least, the machine I would rather have. The quality of the X3 is many steps higher than your X2 (also twice the price). My table is flat within .0003", it has one high spot. Spindle runout is about a tenth.
Every surface which must be accurate, I have found to be excellent. For the most part, the cosmetic stuff has been good as well. The only major cosmetic flaw was that none of the dovetails or bottom of the mill table edges were deburred. These burrs were nasty, my hands got some deep cuts handling this for hte first time. Nobody else has mentioned this, it might just be my instance.
Overall, the quality of the X3 far impressed me. I used to own an X1, which was sub-par in the QC dept. I think they pay more attention to their top dog machine.
By the way, the X3 can handle a 1" end mill with ease.

Deviant
08-25-2006, 09:10 PM
hehe

You guys are killing me.... But I asked for info.

phantomcow is your x3 cnc'd? If yes, what are the specs of your machine. What are the feed rates for normal 2.5D milling and 3D contour milling in aluminum?

That request goes to anyone with a x3 or taig? I'd really like to see some videos of them in their native enviroment.

Thanks for the reply.

dcprecision
08-28-2006, 12:29 PM
HI,

The reason that I say these parts are out of TAG range is that I have gone down this road with simpler parts, I know what the mill can do. Why are you going to make these parts in the first place ??? For the heck of it or are you trying to do business. If you were making just one piece, you might be able to do it in a few weeks time with all that is necessary to fixture, tool and program. If you would be satisfied with a lousy finish and design compromises, you might actually be able to produce 2 sets a day with a TAG mill. The circular profile pockets look fairly deep. I think they would need more power and larger tools that the TAG can handle. I may be wrong about all of this, but I have been earning a living for the past 15 years manufacturing hinge mortising and lock installation tools out of 6063 aluminum for a decent profit, working alone in a 1200 sq ft home shop. Over 30,000 Hinge-Mates sold at $ 120.00 each, not quite Mcdonalds but over 3.5 million $$$ part time.

Deviant
08-28-2006, 12:46 PM
A large part of it is to prove that I can.

Originally, I had planned on having a small workshop to make parts to peddle off to the messageboards/ebay.

I don't think I have any plans to make more than 1-2 compete guns per month. That part above is just an example of what I'm looking at doing.

Those parts I posted above are roughtly .5" thick and 6.5-7" long and about 4-5" tall.

I currently have a mini mill, but I've decided that the working envelop is just a tad bit to small. The problem is that to get a larger working envelope to price jumps exponentially.

Which is why I'm looking at the x3 and the taig. The taig is awesome for the price and the ready to cnc. The x3 looks good for the money. There's alot of iron there. I'm just a little concerned with the fit and finish. However, noone has really complained about that in regards to the x3. So either it's new and not many people have them. OR the quality is there. I wish that the x3 had a larger work envelope though. It would make the choice alot easier. Need to get an expansion table for it.

Also, with the x3. I have to retro fit it. Which will take time.

So to answer your question. This is a hobby that could run into a side business. I'm currently make a very good living babysitting a bunch of highend IT equipment for the man. So I don't expect this to replace my day job. I would like for it to pay for itself, or allow expansion into more tools.

Since I just bought my new house. I don't have a large work area that can allow me to find an old bridgeport to salvage. And I'm really not interested in a round column mill. So that limits what I can get.

phantomcow2
08-28-2006, 01:03 PM
THe installation of some of the kits out there look very easy for the X3. Check out the threads about Syil's kit here in the benchtop forum. Also, take a look at CNCkits.au
They have a nice bolt on setup as well. Both of these appear to be good quality kits, and very easy to assemble.
The only thing is that Syils kit requires a modification to the column itself, this would be easier with access to a larger mill.

Travel for the X3...
A LOT of headroom space, more than I could ever use even with a 1/2" jobber drill on a chuck. I guess I should never say never though.
Y axis is about 6", it could be a bit more. Still, thats more than the Taig.

As it is, the mill gets 16" of X axis travel. If you could make a small modification to the x axis radial support block, you could squeeze out 18" though.

Deviant
08-28-2006, 01:10 PM
Yea, I can get creative and make up for the lack of table travel.

I think I've decided on the x3, but I'm still looking and searching to make sure that purchase is more thought out.

Ideally I'd like to have alot closer to 24-26" on the X. I was actually thinking about making a new base for the x3 on the x3. Then using linear rails in place of the a long dovetail... But again that's long term.

Most of the conversions kits that I have seen are fairly pricey for what you get. The ones from Syil and the company out of austrailia look nice. But I think I can make the parts.

But maybe it's just sticker shock. And the individual parts would be alot more. ((That being for the ballscrew with angular contact bearing setups.))

Deviant
08-28-2006, 03:21 PM
Well I ordered the x3..... I can hear the vacumn sound as it sucks the money from my account.

I hope it turns out to be worth it.

Anyone want to buy an x2. (grins)

phantomcow2
08-28-2006, 05:32 PM
Yea I heard that sound too once :).
DId you order it from Grizzly?

Take it apart, play with it. Clean it, relube it. I think you will be far impressed with the quality of it over the X. I think it is well worth the price. If you ordered from Grizzly and you in the continental US, you will have your mill this week.

The retrofit kits are very expensive. I don't say this often in public, but I think it is an extremely inflated price. I don't know if I would call it rip off, but it is a LOT of money for what you get. I work in a machine shop, I know how how much these things cost and what is involved, and the costs to manufacture such a simple thing are not a lot. And the cost I see for the parts we make are not mass production, we are pretty much a job shop. These people make the same things.

It is far cheaper to do it yourself. The ballscrew most kits use is just regular 5/8-.2
You can get 6ft lengths of this for something like 50 bucks, plus 25 per ballnut. Angular contact bearings would justify the cost if sources used New Hampshire ball bearing products, but I doubt this is the case.

But there is the factor of time. I have not really felt like milling bearing blocks, so I am in contact with Syil to see if he will sell me the X and Y bearing blocks.

S_J_H
08-28-2006, 08:36 PM
DIY conversion gives you the opportunity to design for your best intended usage.
And yep using Thomson 5/8 rolled screw is cheap even with double nuts on each axis. Get creative and instead of buying angular bearings use the stock ball thrusts but add 2 abec5 deep grooves sandwiched between them. Makes a very good bearing block for super cheap.
That's what I did.

I am just about done with my x & y axis on my Grizzly x3. I now have 16" of x travel and just over 8" travel for the y axis with double spring loaded ball nuts on each axis.
I really like 8" on the y axis.
I am leaning toward keeping the z axis acme drive and just improving upon it with preloaded double nuts .
Good luck with your x3. I think you will enjoy it.
Steve

dcprecision
08-28-2006, 08:41 PM
The X3 with servos will be by far the best compromise. It has 10X the capability of the TAG for a similar price. You at least have enough metal present to dampen vibrations and enough ridgidness to push a larger cutter at the correct chip load. If you build an X# servo mill and do a good job, It will be worth the money invested if you sell it. You also have a much more powerful motor and by replacing the gear head drive system with a timing belt, you can easily make a 4500 - 5000 rpm spindle with variable speed. You really need the chip load and surface speed if you want your expensive high tech end mils to last a long time. Good luck with your project.

phantomcow2
08-28-2006, 09:11 PM
Angular contact bearings can be bought for cheap from http://www.vxb.com
I got 3 pairs of 10x30mm angular contacts for 10 dollars a piece. Plus a pack of ten 20mm ID bearings for 6.95

S_J_H
08-28-2006, 09:13 PM
dcprecision, I totally agree with you about the spindle speed. I think it will be pretty easy to get near 5000rpm out this thing with a little reworking.

I was just measuring my z axis backlash off the hand wheel indicated amount vs actual measured spindle movement .
It is an amazingly low .0037". I say amazing when you consider this is through the acme nut AND the 2-1 bevel gear drive and I have made no effort to tighten it up from the factory.
Heck some ballscrews have more than that!

Steve

phantomcow2
08-28-2006, 09:17 PM
I was pretty impressed with my Z axis backlash too. That is about the same as some bridgeports.
The weight of the head pulling down probably makes a difference though. Still, can't complain about quality in this part of it all. It saddens me to see this nice Z axis setup no longer used when my mill is finally CNCed.

Deviant
08-28-2006, 09:31 PM
I bought the mill from Gizzly, I'm hopeful that it will get here this week. Early next at the latest.

Got my capacitors in the mail today. Misc mounting hardware and a break out board. That should complete the power supply and gecko drive system.

Does anyone have dimensions for the conversion blocks. I think I can reengineer them from the pictures. Just don't really care to reinvent the wheel. Is there any modification that I need to make to the z-axis screw. Or does it come in a size that is close to fitting a standard gear?

I'm hopeful that the mill will be good. I'm just a little nervous on any extra money that I'm going to toss at it short term.

I'm hoping that I will be able to get a good cnc conversion using the stock gears, short term. Then upgrade them later.

Does anyone know what the backlash is like on the roton ballscrews? Will they load oversized bearings. I think I remember that they will.

S_J_H, Do you have pictures of your conversion or a parts list?

mhuett
08-28-2006, 11:44 PM
Deviant,

On the retrofit side (and to help with some of your questions) the kit I supply can be fitted in and evening or two ... and it has the added benifit of actually increasing the Y travel on the X3 (and Super X3) by about 1" which is spread evenly front to back.

I don't want to do the wrong thing by posting my site address but if another member cares to add in a link for the PROMiCA site .... ;)


Regards

Marc

S_J_H
08-29-2006, 12:27 AM
Deviant,
I'll take some pics this weekend of my progress. I still need to order the belt drive parts to get it moving under power. I changed my mind mid stream and decided to use 2-1 belt reduction rather than direct drive. To get 8" of Y travel means spacing out the bearing block and I certainly don't want the motor sticking out that far with direct drive.
I think I'll use GT2 2mm pitch pulleys and belts for the very low backlash.

phantomcow2,
That is cheaper than I had thought for the bearings.
I had a dozen deep grooves laying around from past projects so for me it cost nothing. All I can say is my bearing blocks with the factory double ball thrusts sandwiching 2 deep grooves with a nut to take up end play seems pretty robust in locating the screw. Probably more friction and not as smooth as a set of angulars, but radial and axial loads are certainly under control.

I had measured the z axis with and without counter weighting and backlash was the same. Factory did a great job.

Steve

Greolt
08-29-2006, 02:24 AM
.............. but if another member cares to add in a link for the PROMiCA site .... ;)
http://www.cnckits.com.au/

Well worth a look IMO :p

dcprecision
08-29-2006, 12:46 PM
Has anyone thought about using radial bearings on the lead screws ? They do have some thrust capability if the preload is kept low, and it seems that the loading on these small machines will be pretty minimal. I have so far sucessfully used them on the Z axis of the pictured machine with excellent results. I think that I mag get over 100,000 cycles out of them. This head and motor weighs 40 lbs. The main advantage to radials is low cost. I sell packages of 10 pcs of R8ZZ - 1/2 x 1 1/8" for $ 18 + 5 shipping. So what if you change them out once in a while. You can at least get up and running at little cost with good results.

KDN Tool
08-29-2006, 02:39 PM
With my converted X3, I once called a wrong TLO in a program and plunged a 3 flute 3/8" cobalt rougher into 6061 about .175" deep full width of the cutter. The machine then went along cutting at @ 12IPM with 1800 RPM spindle speed. The machine did not like it but it did it anyway, however the cut quality was lousy.(it was just a roughing cut anyway)(I fixed the program after that)
My mill features a 1:1 belt driven VFD controlled 1/2 hp spindle motor. The X and Y have the usual 5/8 X .200 pitch ball screws with double nuts. Bearing blocks use duplex 12mm grooved race thrust bearings with a threaded preload on the ball screws. Gecko G320's with 880 OZ servos direct drive to the ball screws. On the Z I still use the stock lead screw with aforementioned Gecko and 880 oz motor, but with a 3:1 reduction via timing belt.
I have been running this set-up for over two years cutting only aluminum. If you stick with good quality 3 flute roughers and finish end mills, you can get decent finishes from it. I typically leave @.010-.015" for finishing and cut .250" deep with a 3/8" mill.

Ken
KDN Tool

phantomcow2
08-29-2006, 03:39 PM
Radial bearings will work. I have some actuators that use them instead of a duplex.
Just put a spacer between the two inner races, maybe .02" thick. Then the outer races are pressed into whatever the housing, and the inner races end up being preloaded.
It works, but for the cost of duplex bearings from VXB, you might as well use the duplex.

Deviant
08-30-2006, 12:41 PM
Yay...

Grizzly sent me a trakcing number, looks like it will be at the house when I get home.

*muhahahha*

phantomcow2
08-30-2006, 04:14 PM
wow, that was quicker than me. I am about 9 hours from the grizzly warehouse. Took 3 days on the truck

Deviant
08-30-2006, 04:26 PM
Yea.

They are being punk heads. The little note says it's suspose to be delivered today, but they called and want to deliver it tomorrow. I won't be there then. So now they want to deliver it on Friday.

I'm call and see if I can pick it up at the terminal or something.

phantomcow2
08-30-2006, 04:33 PM
If only freight shipping was like USPS :). You should be able to pick it up at the terminal. The freight shipper always prefers this, because they don't need to deliver. They like that enough that they will forklift the package onto your truck or whatever.
I had my package delivered right to my work. The freighters were happy to do this for me (since they deliver almost every day to a neighboring business anyways), and thers a forklift there.

Then you start the strip down process

Deviant
08-30-2006, 04:41 PM
woohoo, called ther terminal here. They said they were open all night and that I could come get it.

*jumps up and down.... that's right!*

Anyway, looks like I will get it tonight. Just have to drive like 30+ miles to get it.

Would be cheaper to wait, but I wants my precioussssss...

Deviant
08-30-2006, 09:04 PM
Got Mill.

Will post pictures of it later.

RAWR!

phantomcow2
08-30-2006, 09:07 PM
Congrats! Check out the quality too :). You will be pleased

Deviant
08-30-2006, 10:22 PM
X3 is safe at it's new home....

Will begin it's cleaning tomorrow.

Burn
09-03-2006, 04:59 PM
To clarify a point, what conversion kits are people using and should I decide to sell my Taig, can people provide links to their X3 CNC retrofit kits? Thanks :D

Deviant
09-03-2006, 06:59 PM
Since you already have the taig. I wouldn't worry about it just yet. Learn how to use the taig. That knowledge should carry over to the bigger mills later.

I imagine that this time next year, I'll be looking at getting something bigger.

But to answer your question.

I've found about 3 different companies that are currently making hardware retro kits for the x3. They are listed on the x3 posts of this forum. I don't have all the links handy though. I found another on google that sells castings for motor mounts. I was going to post here and see if anyone had any ifno.

I'm leaning toward making my own. Using roton or rockford ballscrews. The mill is a really straight forward conversion.

S_J_H
09-03-2006, 09:06 PM
As promised I took a few pics of my progress with my x3. What I decided to do was to build off the factory cast iron dowled bearing blocks and also to base my double nut ball design on the bronze acme nut blocks.
This kept the factory center alignment intact.
The y axis is complete less the belt drives and I still have to make a x axis bracket for thr stepper.
.They operate smooth as can be and have 0 backlash and I mean dead 0. The nuts are spring loaded with a bout 60-70lbs and use 2 stainless 1/4 " dowels to prevent movement.
8" travel for the y axis. I will have 16" of x with a slight mod.
Long way to go but so far so good.
I will be using 3mm GT2 belt drives at 2/1 reduction.
Steve

Deviant
09-03-2006, 09:12 PM
Awesome job.

I was wondering if there was enough clearance to run the ballscrew all the way up to the column. Did you drill a hole in the column, or is that just acting as a swarf shield?

Your layout is almost exactly what I started doodling up. With the exception on the y axis. I mounted both of the nuts on the far side from the column. Then I extended the front motor mount to clear the additional length.

Thanks for the pictures.

S_J_H
09-03-2006, 10:00 PM
Yes I had to drill into the column about 1". Really no big deal. Get a good sharp 3/4 drill. Look at the tip of the 3/4 drill and find a smaller drill that is the same diameter as the tip web of the large 3/4" drill and use that to predrill.DO NOT USE ANY LUBE TO DRILL THE CAST IRON.

Drill the small hole first at least 1'" deep. This allows the large 3/4" drill to easily cut and track the smaller hole. Use a good powerful hand drill with the 3/4" " drillbit and go for it. I bolted my mill down and had no probelm at all going right in with the 3/4" drill with minor effort. IMO stepping drills incrementally is really not good practice and a beginners mistake. 2 sized drills bits and this is a 5 minute job.
Now, after setting up the yaxis for 8" full travel, I have to say it becomes pretty sloppy on the dovetails at the extreme 8" out. I did it it just to have the travel if ever needed.
Anyhow it's just plain fun to try new things.
I was able to tighten the gibs and then run the table back and
forth with the lowest torque setting on my cordless driver at top speed with out the clutch slipping which my 7 year old daughter could stall..
This means friction for the drive is mighty low. The bearing blocks are solid sum b!itches made using the factory ball thrusts sandwiching 2 deep grooves with light oil in the cast iron housings. The x axis I had to add a 7075 extension for the bearing block.
I added hardened 3/8" studs to the yaxis mounts since they were spaced so far out for the extra y travel. I did not think 6mm bolts were sufficient.
The z axis will be simple, I am resusing the acme setup as it is just to good to toss away .
I'll be adding some bearings and a belt drive. A quick disconnect z axis handwheel for good measure.
The X axis will be belt driven I have to design a bracket for that. Originally It was to be direct drive. After much much research I will use a 2-1 belt reduction.
Still some design work to do for that.
Nex photos will be with both axis belt driven with 0 backlash.
Then onto the zaxis acme setup and rotary table 4th axis.
Steve

Deviant
09-03-2006, 10:07 PM
Looks good.

I'll be glad to see it finished.

Where did you get your ballnuts/screws from. You might have told me in another post, but I tend to be everywhere. *lol*

I was thinking about using a single nut with oversized balls, but I'm not sure how that would pan out.

S_J_H
09-03-2006, 10:32 PM
They are cheap thomson nuts from Mcmaster.com
You can add larger balls but you'll never get a true 0 backlash nor will it hold it long term if you did. I tried it.
But a single low backlashed nut can be plenty accurate for most hobby jobs.Heck my .002" backlash with my x2 even with acme's using mach3 comp can make circles almost good as my boring head can.
Steve

dcprecision
09-04-2006, 10:05 AM
Can anyone suggest a design plan for making preloaded zero backlash ball nuts. Material needed for the preload spring, drawing, etc.

thanks

S_J_H
09-04-2006, 11:02 AM
I found a few on this site using search.
I tried to keep it real compact with my design. The mounting block is bored out until it is as close a fit as you can get to the nut thread diameter that still allows the nuts to be installed with gentle hand force.
I then drill the mount for 8-32 setscrews to lock each nut in place. You will only use 1 setscrew in the end though.
I mount one ballnut in the mount and lock it in place with the setscrew.
Then put it in the mill in order to drill the mount and slot the ballnut for the steel anti-rotation dowels.
I use a solid carbide 1/4" end mill. The end mill easily cuts the bronze and then once it begins to cut the side slots in the hardened ballnut, the bronze mount is also working to keep the end mill from deflecting.
You end up with a perfectly aligned slot in the ballnut body and hole in the mount for the dowels.
Then I install stainless 1/4" dowels in the mounting block with high strength loctite. Put the slotted ballnut in the mount to mate with dowels.Make sure no loctite is between dowel and ballnut slot.
Even the best machining may leave a slight clearance between dowel and ballnut slot. So while the loctite is curing clamp the the assembly with light force in a vice. The vice will be clamping the 2 dowels against the ballnut body to take up any minor clearance.
Once the loctite has setup you have a ballnut that can slide fore-aft into the housing but will not be able to make even the slightest of rotation as the 2 dowels in the precise slots will prevent it.
Install that assembly onto the ballnut. Then place a spring inside the mount. I used a cut short section of spring that measured about 60-70lbs to compress.
Install the other ballnut into the mount compressing the spring.I just compressed the spring to a point the screw did not get to hard to turn.
I then lock the non slotted ballnut in place with a 8-32 hardened setscrew. Remove it and the non slotted ball screw. You'll see the markings on the threads from the setscrew.
Now drill a proper dimple to mate with the setscrew.
Reinstall the nut and lock it in place with the setscrew.
It's done.
The reason I use a setscrew instead of threading 1/2 of the mount is that I find it difficult to cut the threads exactly in plane with the bored hole.
If the threads are not exact the 2 ballnuts will bind up. So the setscrew method just makes it easy to keep both nuts aligned.
Steve

dcprecision
09-04-2006, 01:51 PM
Thanks Steve.

I think that I have most of it it, but please clarify. One ball nut is doweled against rotation into the mounting block but can slide in and out of the mounting block.. the mounting block is bored for a close fit to the thread major diameter. the other ball nut is locked in the mount block with a set screw. Is the first set screw used only when machining the dowel pin holes ???

Thanks,
Dennis

S_J_H
09-05-2006, 08:38 AM
Dennis,
You have it exactly right.
The only other thing I did not mention was I lightly sand the major thread diameter with 400 grit to knock off any burrs so the nuts will slide nicer in the mounts.

Steve

dcprecision
09-05-2006, 10:09 AM
Steve,

Thinking a bit further about this type of design, I was considering an alternative design method that may provide greater accuracy. I was thinking that if you set up your mounting block on the mill table and bore the through hole then concentricly machine a square pocket 1/2 the block thickness deep, lets say 1/4" larger square than the nut thread od, using a 3/8" end mill, you could make a corresponding square block with appropriatly radiused corners that would fit within the pocket with 001 clearance. Bore this block to nut thread od, or possibly thread it. This block would be fixed to the threaded end of 1 ball nut with 2 set screws and act as the anti rotation device and slide as a square nut within a square pocket would.

Dennis

S_J_H
09-05-2006, 04:23 PM
Dennis,
Oh I am quite sure you can improve upon my method. I wanted to use the factory x3 acme nut blocks rather than build from scratch. So I came up with a method that would work with the limited dimensions of these mounting blocks.
Rather than mess with measuring out new centers I modified all the factory x3 bearing blocks and nut blocks to work with my ballscrews. They were all nicely dowel fitted from the factory and I had a good known alignment so it seemed a shame not to modify and reuse them and make my life easier. :)
Anyhow, accuracy is not an issue with my design. The anti rotation dowels and ballnuts have maybe .0005" clearance. My table shows 0 backlash on direction change.
Steve

S_J_H
09-05-2006, 04:30 PM
I do like your design idea though! It would be very easy to get a precise sliding fit as well as be easily adjustable for wear or in the event you needed to replace a ballnut.

Steve

dcprecision
09-06-2006, 12:48 PM
Steve,

I do agree with you completely if using the existing nut assembly providing the factory accuracy is ok. My RF is not so good in the alignment department I think, so I am going to make bearing blocks and allow a bit of adjustment in my ball screw bearing mounts to obtain smoothest rotation.

One other thought, Have you or anyone out there considered using or used polyurethane washers rather than disc or compression springs for backlash takeup and preload. Thanks for the help, I do appreciate it.

Dennis

S_J_H
09-06-2006, 04:27 PM
No I did not think about poly washers. Might work better than a spring as they might even provide a bit of vibration isolation.You may be onto something.
Not a whole lot of space between my 2 ballnuts. I think I have .350" or something like that before compressing the spring.
I was thinking about these nuts last night and I was even thinking about making a mini pneumatic spring.
Totally overkill and overly complicated I know. But I missed the KISS 101 class.(chair)

Steve