Shortening toolpost

[JimM]

I've picked up a new (to me) Atlas 10F lathe today and although it's the same as my current one it has a T-slotted cross slide which I think will be much more useful. The only downside is that the crosslide sits about 7mm higher than the old one and I'm going to struggle to get some of my insert tooling to sit low enough to hit centre height.

Thinning out the tooling and toolholders will deal with most of the issue but the other problem is that the toolholder itself will have to sit right at the bottom of the toolpost. In this position the piston will only be working on the top half of the holder and I can't imagine this would be particularly good.

I therefore need to take about 5mm off the bottom of the toolpost (pic attached). As I'm still at the early stages of the learning curve I'm not sure what would be the best way to remove this material so should I be using an end mill, fly cutter or chucking it on the lathes and facing the end ?

Thanks

Jim

 

[Chazz]

I would think any of the three methods would work, but I would most likely use the end mill method as the fastest way to setup and cut. My 9 x 20 (different from the Atlas) I shaved down the compound rather than the tool holder. Just my 2 cents.

Cheers,
Chazz

 

[Noitoen]

Isn't a "commercial" toolpost hardened?

 

[cidrontmg]

Isn't a "commercial" toolpost hardened?

They seem to come in a great variety, some are even aluminium (!). My Dixon-style QCTP in a Myford Super 7 certainly is very hard, as are the toolholders. No way cutting it to size. Grinding 5mm off the bottom might be doable, with a surface grinder - with an awful lot of fine grinding dust... :fan:

Jim: Check first if it´s hardened, before you ruin an end mill...

 

[Twmaster]

I don not understand what you would gain by shortening the tool post. The tool holder is only going to be able to go so far down whatever tool post you use until it hits the top of the cross slide.

I'd also be wary of thinning the cross slide.

Perhaps you could make a couple of tool holders specific to that machine's short comings?

 

[tel]

Yes, but he's trying to get the toolholders to go up a bit in the body - presumably so there is some downward adjustment.

 

[JimM]

Twmster, you're right in that shortening the toolpost won't affect the centre height of the tool itself. The problem is that the toolholder will just about be at the right height if it sits on the crosslide, however when it's that low down on the toolpost the piston is only acting on the top half of it. This my well be OK but my thinking was that it probably wouldn't be as rigid a setup as it could be. By shortening the toolpost I'd be making the piston sit lower and it would therefore be more central on the toolholder.

I may be making life more difficult for myself than I need to as the setup might be OK as is, due to the possibility that the toolpost could be hardened I'm now tempted to leave things as they are and see how well it works !

Hope that makes sense ?

Cheers
Jim

 

[Blogwitch]

Jim,

I had the same problem as yourself, many years ago, when I rescued my Atlas 10F.

This is the only decent photo I have of the area, so I will try to show you how I solved it.

I gather you have the same sized toolpost as I did, a size 100.

Item A

When I got the lathe, it had a fairly bad repair to the top of the compound, and where the toolpost was supposed to fit wasn't very flat. So I milled about ¼" (6.4mm) off the top of it, and made it nice and level. It was relatively easy to do because the compound was made of cast iron. Structurally it made very little difference to the rigidity of the compound.

Item B

By carrying out item A, left the back part of the compound higher then the face I had just machined, so the toolpost could not be rotated.

Item C

I can't remember how much I milled off the bottom of the base, I think about ¼" (6.4mm) again. It cut fairly easy on my old mill/drill with a sharp tool. You can check yours out by just running the corner of a file against a corner of the toolpost, if it doesn't skid off and leaves a cut mark, you should be able to machine it OK.
Once the base was cut off, I then mounted the block into my four jaw and turned a large spigot onto the base, high enough so that the toolpost could rotate without hitting the top of the compound casting.

You can just see how the holder fitted onto the post, almost perfectly central.

The rest is history, as this served me well for many years, and hopefully the new owner after me as well.

I hope this helps


Bogs

 

[Niels Abildgaard]

Hello Jim

Let us see your toolholders with your favourite tools.
What I am hinting at is If you really need to put the QCTP on the compound slide.
Many years ago a rather phenomenal man Radford showed how to make many very good tools for a Myford(Boxfords are better) and his own favourite was an ultra rigid cross-slide without compound slide.
He claimed that the improved rigidity made him happy everytime he used it.
Surfaces got better also.
I only use the compound slide for accuracy that is I put it in 3 degre and then moving compound slide 1 mm gives one tenth of a mm reduction of the workpiece.Rude but works but a DRO will make it unnessecary.
The other compound slide job is threading but having all this iron for mowing a tool 1-2 mm in the rigth direction is crazy.
Ifanger of Switzerland make a very good retacting tool holder that will do a better job.
Is there someone here who can make something even better from scrap steel?
I put on two pictures of a boring bar holder I use everyday.
Imagine the lower part going down to the cross-slide (no compound slide) and compare it to the picture Bogstandard has given us and compare rigidity of tool point.

 

[Twmaster]

Jim,

Ok, I see what you are getting at. However, I think that Atlas compound will fail before the tool post or holder moves even with only half the piston gripping.

I have to say though, gripping only half at a minimum -looks- somehow wrong.