Taig questions (need more power and tuning tips)

[b0gh0s]

I have a Taig CNC mill that I have been using for a couple of months now and I need some advice (I have already done some searches but am looking for quick succinct answers). I am doing mosting standard aluminum milling, (3d parts, slot milling, facing, lots of different operations, mostly prototyping and small production runs). I am running a 4axis xylotex type board and 270oz deepgroove steppers. I am using Mach 2, (couldn't get 3 to work for some reason)

1) I have had several occasions where I have been able to stall the stock 1/4 hp motor using 1/4 and 3/8 EMs doing facing operations (like 5ipm feed and .03 doc in sheet aluminum). What motor upgrades work for this and where do I buy a good setup to do this? I can spend some money on this, I am looking for something reliable, and powerful. Can someone please point me to sources of stuff that has worked well? I did a search here and got a lot of stuff but nothing I feel I can go on...

2), I need some more backlash and tuning help, I put a dial indicator on the ways, adjusted the backlash and the gibs. I got everything pretty tight but if I really push (putting some umphf into it), I can get it to move like .0015 each way on my dial indicator, any tighter on anything, I start stalling the steppers, can anyone recommend a more directive set of steps to adjust the ways so that I can get close to holding closer to .001?

3) I have the spindle speed cranked to the highest RPM I can get, I can run like 5ipm slot milling with a 2 flute at doc of .06 with a 5/32 em, is this too aggressive?

Any help would be most appreciated, I am totally hooked on CNC stuff, I have tons of parts and prototyping I am doing, if I am not checking something or if I need to provide more info please let me know, I am a relative noob...

[b0gh0s]

Also I am using a Hightechsystems LLC quick tool changer, has any one else used this with good/bad luck? Any thoughts on this or is there any additional tuning steps I need to take for using this type of changer?

[cartertool]

Originally Posted by b0gh0s 1) I have had several occasions where I have been able to stall the stock 1/4 hp motor using 1/4 and 3/8 EMs doing facing operations (like 5ipm feed and .03 doc in sheet aluminum). What motor upgrades work for this and where do I buy a good setup to do this? I can spend some money on this, I am looking for something reliable, and powerful. Can someone please point me to sources of stuff that has worked well? I did a search here and got a lot of stuff but nothing I feel I can go on...

Is the motor stalling, or is the belt slipping? I have never stalled the new motor. If you are stalling it then you aren't removing material fast enough so you need to reduce your DOC or your feed. Are you using lube/coolant on the work?

Originally Posted by b0gh0s 2), I need some more backlash and tuning help, I put a dial indicator on the ways, adjusted the backlash and the gibs. I got everything pretty tight but if I really push (putting some umphf into it), I can get it to move like .0015 each way on my dial indicator, any tighter on anything, I start stalling the steppers, can anyone recommend a more directive set of steps to adjust the ways so that I can get close to holding closer to .001?

If you are pushing on it and getting a little extra backlash, chances are that's due to compression/flex. Don't worry about it so much. Cut some sample parts and see if it is coming out right. A good test is to mill a circular boss or pocket and see that it is round - don't worry about the dimensions, just that the x and y measurements are equal when you use a mic or caliper on it. You really shouldn't be trying for more than about .001" accuracy, especially if you are new to all this. Let the machine tell you how it is working.

Originally Posted by b0gh0s 3) I have the spindle speed cranked to the highest RPM I can get, I can run like 5ipm slot milling with a 2 flute at doc of .06 with a 5/32 em, is this too aggressive?

If it works, it isn't too agressive. It's hard to go too fast in aluminum...The problem is that with smaller cutters they flex, and really can't remove that much material per revolution. Start researching proper speeds and feeds and how to calculate them (get a copy of machinery's handbook). Generally DOC should be no more than half the diameter, so .06 is ok.

subscribe to taigtools yahoogroup...

[b0gh0s]

Hey Nick, thanks for the reply.

OK so I have done a bunch of round cuts on this machine already, (lots of small bearing blocks and the cuts come out pretty darn round, as far as I can tell a perfect circle and usually a good fit for the bearings I put into them.

With the stall, I actually stalled the motor, no slipping, just a complete stall.

Does the 1/2 diameter hold true for slot milling? Basically I am clamping a piece of .25 in alu sheet into a good vice and trying to mill it out. I have a complex outline (lots of curves and cutouts) and I can't figure a better way than to slot it out using passes. For some reason I seem to have a harder time running the larger EMs than something like a 5/32. I can run a tiny 3/32 at 5ipm at .03 doc all day long at the same spindle speed and it is quiet as a mouse, but the larger EMs seem to have a harder time and make a lot more noise. I tried dropping the plunge (z feed?) down to like 2ipm but still stalled the system with the larger EM.

I have tried both 2 and 4 flute EMs in this size with the same results.

Will more HP fix this?

Also I am having a hard time discerning what is chatter vs noise from a larger cutter.

[b0gh0s]

I am using cutting oil brushed onto the EM, I also have air blowing across the EM and a Vac hose on the other side sucking out the chips. The EM does not look like it is getting hot but I am not experienced enough to tell this with certainty.

[b0gh0s]

Also is there a better tool for slot milling? If I am trying to cut a part out (for instance cut out an aluminum circle .25 inches thick from .25 in material), and I want to get a cleaner cut on the outside edge?

[cartertool]

Do you really have the 1/4hp motor? It's blue and from Franklin electric...
If it's stalling then I don't know what it could be...Try lowering the speed when using larger cutters and see if it handles it better.
If you have runout on a cutter it will make more noise, are you using collets or some aftermarket endmill holder?

You should be able to use a 2 flute endmill to profile shapes out of sheet no problem.
They do make endmills specifically for aluminum, but a general purpose 2 flute endmill should work fine. Where did you buy your endmills? HSS or carbide?

It's hard to really diagnose problems like this without being in the same room - do you have a mentor or buddy who has more machining experience who can check out your setups and procedures (and the general mechanical setup of the machine)?

[b0gh0s]

I don't have a mentor or buddy.

I do have an aftermarket tool holder from hightechsystemsllc.com I used shim stock to try and get the tool to have as little runout as possible.

With the large em, I forgot that I had the pulleys setup for the highest speed, (largest motor pulley to smallest spindle pulley). I will try to set for a more reasonable ratio and try it again.

As for the EMs, I only buy carbide, been experimenting with TIAN or TIALN or cobalt coatings, TIAN and TIALN seems to work the best for me.

In looking at this problem I guess I am more after the ability to vary speed and have more power without having to stop and change pulleys in the middle of the part. I have built offsets and profiles to allow cutting parts with different tools for different operations but I think will really require different speeds (not just different feeds).

Like I mentioned before I am ok with spending some money on a good motor and control setup for it, I just don't know what the recommended motors are that have worked for others who convert.


My current motor is the stock Franklin electric, (didn't give a Kv specifically it just listed 3200 RPMs if I remember the label right)...

[PaulWCSR]

I have found the manufacturing calculator that comes with AutoEditCNC, for free, works great with my Taig for feeds and speeds. Lets you select the material, tool type, chip load, etc.

[bkstout]

here is my suggestion from my past year with my taig no problems with 1/4 " em lower your spindle speed to the half way range on the pulleys program at the feed of 10" a minute and take a .02 doc an see how this works for you i am not familiar with your tool holder this could be your problem i use collets an have never had any problems with accuracy or stalling if at first you don't succeed try try again!

[b0gh0s]

Well after much cursing and some bloodied knuckles I finally changed my tool holder out and put in the ER spindle/collet setup and I was able to see the difference immediately in the finish on the same parts using the same tools and same G code.

I still like the idea of going to a variable speed setup that I can program the RPMs for in code, any one have any suggestions?

BTW the bloodied knuckles were from trying to get the damn pulley off, for some reason it was really tight on that spindle and I had to use a heat gun and large wrench to pry it off.

[cartertool]

I just made a stop for my ER spindle so that I can change tools repeatably:
Spindle Stop

As for speed changes, get a Sherline or other VS motor that uses a KB speed control and see if you can get Peter Homann's Digispeed to work...
digispeed

Yes, you usually need heat to remove the pulley, and it usually ends up being a frustrating experience...

Originally Posted by b0gh0s Well after much cursing and some bloodied knuckles I finally changed my tool holder out and put in the ER spindle/collet setup and I was able to see the difference immediately in the finish on the same parts using the same tools and same G code. I still like the idea of going to a variable speed setup that I can program the RPMs for in code, any one have any suggestions? BTW the bloodied knuckles were from trying to get the damn pulley off, for some reason it was really tight on that spindle and I had to use a heat gun and large wrench to pry it off.