Atlas Lathe Milling Attachment Vs. Mini Mill

I appreciate all the replies. After fighting with my milling attachment for the last couple of weeks I am more determined than ever to get a benchtop mill, but probably something beefier than the little 200 lb mini-mills. Time to save some $$$!

I will say that getting a 6 flute high $$$ Niagara endmill did wonders for my Atlas' milling performance.
 
I'm currently using the milling attachment to make the T-nut for the QCTP mount. As has been said it lacks rigidity and vibrates profusely, additionally several times the endmill has knocked the milling attachment off axis whether due to the vibration loosening the set screws enough to allow the endmill to move the assembly when the cutter comes into contact with the work at the beginning of a cut, or some other factor I'm not sure. I'm taking cuts of 0.005 at 430 RPM according the the manual for my Atlas 10100 Mk.2 using the endmill holder that's for the milling attachment. I've had to reset the work several times due to the cutter knocking the setup out of alignment. Using a Hertel 4 -flute 1/2 in. endmill since I haven't made any of the adapter sleeves for the endmill holder yet.
 
First, confirm that you are NOT doing Climb Milling. The spindle should be rotating CCW as seen from the tailstock. If the end mill is above the T-nut, before starting a cutting pass, the Milling Attachment and T-Nut should be behind the spindle (on the far side from the operator) and thus have to move toward the operator in order to cut.
 
wa5cab said:
First, confirm that you are NOT doing Climb Milling. The spindle should be rotating CCW as seen from the tailstock. If the end mill is above the T-nut, before starting a cutting pass, the Milling Attachment and T-Nut should be behind the spindle (on the far side from the operator) and thus have to move toward the operator in order to cut.
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That's how i have been running it... T-nut behind and below the the end mill feeding toward the operator (counter clockwise rotation of the cross feed handle). Tightened up the gibs on the cross feed base that the milling attachment mounts to. Dial in 0.005 depth of cut (counter clockwise rotation of milling attachment handle) and feed work into cutter slowly. I was specifically warned AGAINST climb milling when I first asked about the milling attachment and followed those instructions to the letter to make sure I didn't damage anything when setting up to use the milling attachment.

For some reason I have yet to pin down to a definite cause, the end mill will bite into the work hard enough to knock the entire setup off axis. This only occurs at the beginning of a cut and after several cuts have already been made. Which is why I'm thinking perhaps the vibration is causing the set screws in the milling attachment base to loosen over successive cuts despite being tightened to the point of actually flexing the hex key wrench. Going forward I'll be checking the tightness of the set screws after a few cuts to make sure everything stays locked in place.

I have another 0.041 in. to remove to reach the target dimension of 0.216 on this side. I'll then need to cut another 0.207 off per side to reach the 1.163 in. dimension to fit the T-slot on my compound. The measurement on the stock supplied with the QCTP to make the T-nut were 1.750 in. length X 1.578 in. width X 0.356 in. thickness.
 
Can you post a picture of your setup? ETA how is the work mounted in the vise?
 
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One other thing to check, although I don't claim this is the only culprit, is the gib material. Beginning around 1973, Clausing began changing all of the gibs in the 6", 10" and both 12" except for the Carriage Gibs from steel to plastic. This includes the cross slide gib (which is also used as the vertical slide on the milling attachment) and the compound slide gib (which isn't used when you are using the milling attachment). I am pretty sure that all 10100's have plastic gibs. Your milling attachment, if originally painted gray, may still have a steel gib. If painted blue, it probably has the plastic one. In any case, it is worth checking. The plastic gibs are white or off-white.
 
chippermat said:
Can you post a picture of your setup? ETA how is the work mounted in the vise?
Click to expand...

Sure...the first pic is of the overall setup AFTER a cut has been made to better show the work in the vise, all cuts are made by pulling the work under the cutter to avoid climb milling. The second pic is a close up of the work and at the front edge of the cut if you look closely you can see where the cutter knocked the setup out of alignment and bit into the corner of the work at the front vertical edge of the "T".

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bZudrMSl.jpg
 
wa5cab said:
One other thing to check, although I don't claim this is the only culprit, is the gib material. Beginning around 1973, Clausing began changing all of the gibs in the 6", 10" and both 12" except for the Carriage Gibs from steel to plastic. This includes the cross slide gib (which is also used as the vertical slide on the milling attachment) and the compound slide gib (which isn't used when you are using the milling attachment). I am pretty sure that all 10100's have plastic gibs. Your milling attachment, if originally painted gray, may still have a steel gib. If painted blue, it probably has the plastic one. In any case, it is worth checking. The plastic gibs are white or off-white.
Click to expand...

THANKS !! I had bought some of the steel gibs for the cross slide and compound back when those were offered for sale here & installed them on the lathe as soon as they arrived. It never occurred to me to check the gib of the milling attachment itself. That may well be a contributing factor. I did cranks down some more on the cross slide gib to improve rigidity as much as possible to the point where there is significant drag on the cross feed handle when feeding the work into the cutter, which seemed to help some with the vibration. I reached the target dimension for depth of the "T" this morning after several cuts, though I still need to cut the edges of each side back by 0. 208 in. to get the fit of the slot in the compound correct.
 
This thread has been resurrected in a timely manner for me. I got one of the Atlas lathe milling attachments (could be a Model 500A) with my used lathe, and I have no intention of using it. In fact, I currently have it for sale. However, this thread possibly has me re-thinking selling it. I do have a Taig mill that works pretty nicely for my purposes; that is why I decided to sell the attachment.
 
@56type,

OK. Although there might be other reasons to avoid doing it (lack of visibility being one), if with everything positioned as shown in your most recent pair of photos taken after completion of a pass, you were to raise the vertical slide on the milling attachment by the thickness of the wing on the T-nut plus the diameter of the cutter minus the DOC (Depth Of Cut), that would not be a case of climb milling, either. But it would be harder to see what you were doing and it would be trying to lift the milling attachment and cross slide. Both of which are not desirable if you don't have to do it that way.
 
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