Oh boy.....

[Vicanic]

So I have my taig cnc mill, and I'm trying to set it up. I've been working on it on and off for close to 18 hours now (about 3 hours a day for 6 days)

I have a 2x2x3 square block of aluminum that I am taking .001-.002 cuts off the top.

I am using this vise:
LittleMachineShop.com - Vise, 4" CNC Mill

It is awfully big on the table, but I needed the capacity for the project I got the mill for in the first place, and didn't understand how large this thing was when I ordered it. I imagine if I can get this thing working, I can snatch the leadscrew out of this vise and make a new one with a smaller profile.

I am using the 1/2in cutter here:
LittleMachineShop.com - End Mill Set, 6 Piece 2 Flute

I used this dial indicator to line up the column:
LittleMachineShop.com - Dial Indicator, 1" x 0.001"

On a full pass on the X axis the indicator moves about 1/4 of .001, as far as I've read that's pretty darn good.

My problem is this:

When I'm taking a cut off the aluminum block, I'm passing over it on the X axis, shaving off .001-.002, then making a 1/8in step on the Y axis, and passing over it again, over and over until the surface is done. It always leaves ridges that run along the X on the surface.

I've tried tightening all the gibs, and I've tried adjusting the X and Y gib. That had 0 effect, except of course the hell and a half of readjusting them to get the machine running smoothly again.

I've tried shimming the dovetail headstock mount. I don't actually know if that is where you are supposed to place the shims in order to adjust the Y axis, but I read somewhere that to adjust any misalignment with the Y axis to shim something up in the general toolpost region, and after inspecting the area, the only place it made sense to put a shim was behind the dovetail headstock mount. This has produced extremely erratic results. I have been using pieces of paper about 2.5in long, 1/3in tall cut off the back of the littlemachineshop catalog.

on top of that I think the table might be warped. When I was tramming the head on the X I mounted the indicator in a collet and passed it over the X axis of the table. It was smooth motion of the needle for all but about 2 inches of the table, slightly off center, where it would have a sudden drop and rise of about .002. I've tried giving it a little rubdown with 400 grit wetdry, it seemed to help a bit, but not completely.

This is insanely frustrating me. The only reason I have given it about 3 hours a day is because I have to take the rest of the day to cool off after 3 hours with this machine. Can someone please help. FYI I am not a professional, nor do I have any experience in a shop, or any shop buddies I could call.

Thank you for your time.

[cameraguy]

sounds like you need a fly cutter, not a mill. also, what kind of stepover are you using? Also, why take so little off with each pass?

[Vicanic]

I'm only taking off so little per pass because I am just using this to check for accuracy in tramming the head. I'm using a 1/2in cutter and 3/8in overlap per pass. I'm intending to use this machine for cutting molds for very small parts that need to be quite accurate, so I'm trying to get it dialed in.

[Bwana Don]

Silly qustion but, did you tram the head in with an indicator? You say your not a proffesional so I'll start with the basics and we'll go from there.

Good luck. Machining can be very frustrating at times.

[awerby]

Before removing any more material (with your sandpaper), which will usually cause more problems than it solves, make sure you've eliminated obvious causes of error, like little pieces of grit that might be lodged at the base of the column where it bolts onto the bed. Taigs are machined pretty well, and there shouldn't be much error front-to-back, but that could certainly cause some. Once you've disassembled and inspected that, and perhaps the place where the spindle assembly attaches as well, then check tram with an indicator, like Bwana was suggesting. You can shim, if necessary, with aluminum foil or other very thin material inserted into the joint between the column and base until the indicator shows no difference between a front and back position.

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[Vicanic]

I did tram the X axis with an indicator, however I didn't have a block ground parallel to put on the table to tram the Y with the indicator, I didn't want to bust the tip off in a T-slot. But I just now realized I do, I have one of these precision ground mold blocks I intend to cut So I will be doing that in a couple of hours, post results. Sorry for the mess.

[Vicanic]

so the three things I need to do are this:

tram the X

tram the Y

ensure parallelism of the headstock dovetail mount

what order should I do those in, since as far as I can tell they are all very interconnected.

[BSAMachines]

Hi,I know this is off topic and I'm new,but how do I start a thread?

[Vicanic]

So using the dial indicator, I trammed all the axes. I'm gonna remount the spindle and motor mount and run it again tomorrow on surfacing the block, to see if I'm still getting ridges. If so, I know it isn't tramming that is the problem.

[desktoplathes]

I can almost guarantee that you are out of tram.

General Tramming Procedure:
1) Align the vertical Z column perpendicular to the X-axis.
2) Align the spindle headstock perpendicular to the Y-axis.
3) Align the spindle headstock perpendicular to the X-axis.

So the above is the order I tram in and it's the easiest way I've found to proceed without "undoing" any previous efforts.

1) Get that Z column lined up as best you can. Start with a machinists square and eye-ball it. Next attach your dial indicator to the headstock, and a 1-2-3 block on end to the table. Run the headstock up and down so that your dial indicator runs up and down the 3" side of your block. Does it travel over this distance? If so, you need to adjust the column as it is not perpendicular to the X axis. This is probably the hardest thing to get right, as the column will slip a little each time you tighten it. Also, don't overtighten the column! Chuck up on that wrench with your hand. Be sure to clean up the mating surfaces of the column as well - use a green scratch pad or similar.

Sweep the table by attaching the indicator to the spindle and rotating it from one side to the other with a 123 block on one side and then slid over to the other. Always make sure things are wiped clean of debris as it doesn't take much to make your measurements come out wrong. If it's off, then your dovetail needs adjusted and possibly shimmed. There are two ways to adjust the dovetail - rotating it slightly before tightening the bolts down (this affects the X-axis perpendicularity, and shimming the top or bottom to tilt it (this affects the Y-axis).

2) You want to now work on getting the headstock perpendicular to the Y axis. This can be done by shimming between the dovetail and the column. This should be pretty good from the factory so it's only something I'd do if I really wanted things perfect.

3) After shimming the dovetail, it's time to try and tighten it down in such a way that the headstock aligns perpendicular to the X-axis. This adjustment is made by rotating the dovetail slightly before fully tightening the fasteners.

There are several ways to do 2 and 3 but the most straightforward is to sweep the table with each adjustment. Alternatively, #2 can be completed by mounting your dial indicator to the table and running along the dovetail surface as you move the Z column up and down. A similar approach can be taken with #3 and using the angled edge of the dovetail.

I suspect if you are to get #1 right, you'll take out most of your issues with the ridges that you're seeing. A note about your observation that there was almost no variability along the X-axis ...If you're taking this measurement by mounting the indicator to the headstock and running the x-axis underneath it, then it doesn't matter how poorly the column is aligned, it will read the same good numbers. This is because you are actually measuring the variability in thickness of the table. Hope that helps! -Keith

[Bwana Don]

Good procedire form desktoplathes!

Remember tramming is always done without moving X or Y. You're just swinging the indicator in the spindle.

I can almost guarantee it's a tram issue also.

[Fixittt]

if you do not have a flt surface to work from, lay a small sheet of glass (think picture frame glass) on the table and swing your indicator around on that. That will help you get really really close.