Can't tighten down my quick change tool post due to Grizzly's poor design

[stioc]

I have a AXA QCTP that I purchased from Little Machine Shop but I can't seem to tighten it down well. The reason why I can't tighten is because the tool post stud that came with the lathe (LMS supplies an adapter sleeve that threads into this stud) doesn't seem to have a locating pin nor splines nor any other kind of a stop https://www.grizzly.com/parts/Grizzly-TOOL-POST-STUD/P4000908 so as I tighten the QCTP nut down it starts to spin the whole stud. Upon doing research it seems the older versions of the 9x20s came with the bottom of the stud splined. Not anymore

To fix this I'm thinking of cutting a flat slot across the bottom of the toolpost stud and a matching slot on the compound body underneath then welding a section of a drill bit into the slot on the stud to sort of make a T. That will prevent the stud from turning once the drill bit section finds the matching slot in the compound body. Never welded a hardened drill bit before but should weld like any other steel with mig?



Another idea was expoxying (JBweld) an allen head bolt to the top of the adapter sleeve (it's hollow at the top) which threads into the stud. This way I can hold it in place with an allen key while tightening the nut down.

LMS suggested knurling the bottom of the stud (sorta like splining it) but not sure if that will help since it's not a tight press fit.

Any ideas/suggestions?

 

[mikey]

I can think of several options, just to throw something out there:

• Drill and tap a hole in the side of the compound for a set screw that would bear on a flat milled into the side of the stud.
• Use permanent loctite to put a sleeve on the bottom of the stud, then loctite that assembly into the compound. You can get it out with a little heat if you have to.
• Another option is to press the sleeve/stud in place and then lock it it with a roll pin. The hole for the roll pin would be centered on the edge of the large diameter at the base of the stud, such that the hole cuts into both the large diameter and the edge of the hole in the compound. This hole must be drilled all the way through the compound so you can get the pin out but this is how Emco locks their studs on the Compact 8.
• Knurl the base of the stud as LMS suggest but also loctite it in.
• Make a new stud that will press fit properly into the existing hole in the compound. I would still loctite it in.

I'm sure there are many other options ...

 

[stioc]

@mikey thanks. So far I like the idea of a keyway or a rollpin like you suggested as those would be the simplest/quickest (provided I don't break the 1/16" drill bit in the process) but I'd have to check to see how much room I have on the big diameter of the stud.

 

[mikey]

I would suggest at least a 1/8" diameter roll pin if you go this route. If you do this, be sure to put a spacer/washer/nut over the stud and lock it solidly so the stud cannot move when you drill it.

I'm interested to see what the other 9X guys did.

 

[savarin]

Heres how I did it.

The 9x20 Mods Thread

My 9x20 has a couple of mods including a qctp and 4 bolt clamp for the top/compound slide. I have noticed there is still a fair bit of flex under some conditions, parting being one. The fixing bolt for the qctp is still the original skinny one but with spacers. I will be drilling and tapping the...

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At post 12
But after going down the 4 bolt clamp, pitkin doughnut route I eventually made a solid plinth and removed the top slide completely and only replace it for small tapers. I do heaps of single point threading with no problems.
I think that all the flex in the standard top slide assembly is worth removing by the solid plinth.

Plinth For Qctp On 9 X 20 Lathe

In my never ceasing search for more rigidity in my lathe I decided to make a plinth for the qctp. In its normal configuration I can often see the complete top slide assembly flex slightly. (I think I punish my lathe a bit) After seeing Bill G's plinth I felt it was time to go. I forgot to take...

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I also removed the detente plunger as I found it annoying and set a paper shim between the tool post and base,
And get rid of that pathetic excuse for a 4 jaw that comes with the lathe you wont believe the difference a real one makes.

 

[stioc]

@savarin thanks for the example. If I'm understanding it correctly looks like you drilled/tapped the stud that came with the AXA toolpost and threaded a screw from the bottom?

What 3/4 jaw chuck are you using now? how much do they run? I know I want the G4003G or the equivalent PM lathe down the road so I'm trying to avoid investing too much into the 9x20. Of course, I still want it to be useful until then

 

[stioc]

OK so I ordered the roll pins from Amazon which should be here on Wed but I believe I've fixed it already haha. As soon as I got home I ran into the garage and started figuring out the next move. Unfortunately the large diameter of the stud was barely 3/32" bigger than the stud and even then it would've required very precise drilling. However I noticed that there was some friction as I pushed the stud in and out of the hole. I cleaned the hole and the stud with brake cleaner and now I could feel even more resistance but not enough to keep it from turning under the load of a wrench. So I decided I was going to create friction everywhere. I put an emery cloth on the surface place and scraped the bottom of the AXA TP, and the top of the compound rest where the TP sits. After that I decided to knurl the bottom of the stud as LMS suggested. The only problem was I couldn't do the knurling on the lathe...or could I?

Folks don't try this at home...but I couldn't come up with a better option

At 120 RPM and using my (now tired) fingers to push the tool into the stud for a good 30 mins I thought I had enough of a knurl to give it a try...and wow to my surprise I couldn't beat it into the hole with a small hammer. I put red loctite on it, grabbed a bigger hammer and a punch and set it into it's place

I was able to tighten the AXA TP fairly well at this point but I didn't want to overdo it until the loctite was dry. But I had my lathe back and I wanted to back up my work by driving an allen head into the hollow center of the stud sleeve. So I chucked up an appropriate sized bolt. Turned it down to about .04" oversized. Knurled it and then pressed it in with red loctite.

It was a very tight fit, I was afraid it might splay the hollow top so I threaded the nut around it...which later had a slight bit friction but not bad.

It's fully seated

A quick test and all seems well. I think the knurled bottom of the stud+red loctite alone should be plenty to keep the stud from spinning...so the hex top was more belts and suspenders. I love it when my hack job plans actually work better than expected

Thanks to @mikey and Chris from LMS for the knurling suggestions...I never would've thought that knurling actually makes a tighter fit almost like the teeth are raised and you actually gain some diameter.

 

[mikey]

Where there's a will, there's a way! Glad you got it sorted, stioc. I bet that lathe will hog aluminum now!

 

[Aukai]

Congratulations!
Just checking on a safety note for the press picture. Is the press plate that the vice is on a steel plate, or cast iron? They are moving away from cast iron plates now because they shatter, and fly apart under load.

 

[savarin]

@savarin thanks for the example. If I'm understanding it correctly looks like you drilled/tapped the stud that came with the AXA toolpost and threaded a screw from the bottom?

What 3/4 jaw chuck are you using now? how much do they run? I know I want the G4003G or the equivalent PM lathe down the road so I'm trying to avoid investing too much into the 9x20. Of course, I still want it to be useful until then

Thats correct, your slide may be different to mine though.
It was just a generic cheap 4 jaw, I had to make a back plate for it.
See here.

aligning the holes in the back of a chuck.

My new 4 jaw chuck has 4 8mm fixing bolts on the back but the holes do not go all the way through so I cannot use a transfer punch. I need to transfer the hole centres on the chuck to the back plate so I can drill them. 1) How can I do this accurately? My first thought (only one actually) is...

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