AXA or BXA Tool Post

[davidpbest]

Old thread, new question.

Has anyone else had an issue with getting a boring bar high enough with a BXA on a PM1340GT?

I had to bore some 5/8 holes, and all I have is a 1/2 drill, and then a 3/4. I have a 3/8 boring bar, but when I put that in a 200 series holder, I am still not on center after raising the holder as high as it will go. For my boring bar holder, I have to raise it all the way to the top to get my bar to the correct height. Is this just because I am on the edge of a size change?

I know I could shim the 3/8 bar, but I’d rather not. Maybe take 1/4 off the top?

Suggestion: make an elevation fixture rather than shim or modify the holder. See attached (this is for an Aloris #71 parting tool but works just the same for a boring bar QC toolholder).

 

[benmychree]

Perhaps make a spacer under the tool post.

 

[MrWhoopee]

Rotation of the TP while knurling is a very common problem with a bump knurling tool. If you can generate that much pressure while parting you're a braver man than I.

 

[Christianstark]

I part using power feed. Even tool steels cut well like that but I had the tool post turn on me once. The tool post that came with the lathe had a pin that would prevent that, but the bxa is just held down by a single through bolt. I repurposed the handle and bolt that came with the lathe. Maybe I should make a new bolt and handle with finer threads and or a longer handle to improve my mechanical advantage.

 

[Just for fun]

What tool holder do you have? I have the PM quick change tool holder; it's been a while since I looked at it but if I remember correctly the hold down bolt is larger than the stock unit. You are not bottoming out on the large T-nut that's in the compound are you?

 

[Christianstark]

What tool holder do you have? I have the PM quick change tool holder; it's been a while since I looked at it but if I remember correctly the hold down bolt is larger than the stock unit. You are not bottoming out on the large T-nut that's in the compound are you?

It’s a Bostar BXA. I cut the T to be just below the level of the compound.

 

[Ben A Gonna]

Hello All
I realize I'm late to the tool post party. Getting a 15 in South bend ready for paint, and would appreciate your suggestions, or thoughts as to what , or which QCTP, to use on this old lathe. Reading some of the earlier posts, you all seem to have been there done that. My experience is with the old rocker style post and the old L/H. R/H and straight tool holders.

Thank you.

 

[Dabbler]

@Ben A Gonna I still use my American Rocker tool post from time to time. 75% of the time I use my 4-way tool posts. So much that I have purchased 4-way tool posts for my lathe that didn't have one (I have 3 lathes, 12X37", 14X40" and a 15X60").

But I also own Aloris-style QCTP for all my lathes (a genuine one for the big lathe), and a Dixon tool post for my 15" lathe.

You can do good work with HSS on your rocker, so I wouldn't be in a rush. I am arranging a borrow of every type and size tool post to see which ones are more or less rigid, and what the repeatability of the various types are. I am recovering from a bad auto accident and then Covid, so things have... slowed down.

I'm working towards making my initial findings available by spring.

 

[Ben A Gonna]

Thanks Dabbler
Sorry to hear about the auto accident, and the covid, that crap was no fun. Have used the older tooling for years, and dont have to be in a hurry, just wanted to update a few things, maybe make things more simple.

Best wishes .

 

[Eyerelief]

I have an Aloris CXA wedge type on my 16”. I couldn’t be happier. Lots of CXA size holders can be had at great prices on eBay if you are patient
As @Dabbler noted, plenty of good work can be done with a rocker as well.