Taig headstock sliding down when cutting aluminum

[Bearded_Comrade]

I have a taig mill that I converted to a CNC. I have been using it for the past 2 years for cutting wood. Recently, I tried cutting aluminum, and I noticed that the headstock slides down when cutting aluminum. I saw on the forums that some other people had this issue and fixed it by tightening the bolt on the headstock. However, this did not resolve the issue for me. Here is a video of me hitting the headstock with a mallet. The hits are moderate-light, but the headstock still slides down.



Do any of you know what could be the issue?

Thanks!

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[Eldon_Joh]

drill the spindle through to the other side and tap it with 1/4-20 and clamp it like this
http://johansense.com/bulk/taig/ER-16spindle_mod3.JPG
http://johansense.com/bulk/taig/ER-16spindle_mod1.JPG
http://johansense.com/bulk/taig/ER-16spindle_mod2.JPG

[desktoplathes]

Are you sure the end mill isn't being pulled down into the material? What kind of cuts are you attempting (depth, diameter, feed rate)? Those are pretty heavy hits on this little machine. You might not expect that dovetail clamp to hold up to those kinds of blows, even when properly tightened.

[Eldon_Joh]

the problem i had was it being pushed up. its pretty loose in his video, could probably double the torque on the 10-32 holding the dovetail clamp on. problem being its just not a secure design.

[Ican]

I don't know the history of this particular Taig mill. I can tell you that something is worn a little or the machine has at some point not been used as intended. I have used these mills for 25 years and never seen that problem. Any of these smaller machines simply cannot be used like a 4 ton floor unit. We cut stainless, aluminum.... whatever we need to cut without problems.

Put a thin piece of brass shim stock (very thin) on the side where the head stock tightens and see if that eliminates the problem. That will tell you if there is wear that a simple new part might fix. Of course.... whacking a machine with a hammer is not too advantageous to solving any machine problem.

[awerby]

The BFH should be the last resort when dealing with machining issues. If that's the usual way you treat your mill, I'm not surprised it's having problems. There are delicate bearings in there supporting the screw that you're harming when you whack it like that. It seems that any slippage should be in the other direction (upwards), since the main stress on the dovetail would be when you're plunging into the stock. Aside from the hammer blows, what makes it slide down?

[Bearded_Comrade]

@Ican - using a thin sheet solved the problem. THANKS!

The history of the machine - I've used it moderately in the past 2 years for woodcutting, nothing near abusive. I was hitting it with the mallet to see if after tightening the dovetail clamp it would still slide down. I would rather test it before making actual cuts.

The cuts that pulled the headstock down were pretty moderate - 0.1 in depth and width with a 1/2 in endmill in aluminum. After the fix, those cuts were done perfectly fine on the machine.

[Ican]

@Ican - using a thin sheet solved the problem. THANKS!

The history of the machine - I've used it moderately in the past 2 years for woodcutting, nothing near abusive. I was hitting it with the mallet to see if after tightening the dovetail clamp it would still slide down. I would rather test it before making actual cuts.

The cuts that pulled the headstock down were pretty moderate - 0.1 in depth and width with a 1/2 in endmill in aluminum. After the fix, those cuts were done perfectly fine on the machine.

Good! I am glad that helped. The cut you describe is too heavy for the machine if you did a straight plunge into the material with the .500 diameter tool. I have used and sold these machines for 20+ years and I can promise you, that will cause more problems than you can harvest. Alot of users somehow decide these can be used like Haas vf3 machines and they simply are mistaken. Good luck with the unit. Throw that hammer away!

[desktoplathes]

@Ican - using a thin sheet solved the problem. THANKS!
,,,The cuts that pulled the headstock down were pretty moderate - 0.1 in depth and width with a 1/2 in endmill in aluminum. After the fix, those cuts were done perfectly fine on the machine.

Ok, so those cuts sound pretty huge for a Taig mill.. Do you recall the feedrate? how many flutes? I'm surprised the 1/4 hp motor kept up. I'm guessing you had it set to the lowest RPM? If you can post a video of that cut, I'd be very curious.

[awerby]

It sounds like that 1/2" tool hung up in the aluminum, grabbed and pulled. Yes, as Ican says, that's too big a tool for your machine. There's a reason that the largest collet it takes holds a 3/8" tool. How were you holding that thing - in a home-made toolholder, or did it have a reduced shank? With a small CNC machine like the Taig, you can take multiple light cuts quickly, with a smaller tool, and get the same results as a bigger mill taking a heavier cut with a larger tool.