A&R Precision tool Post

This topic has 7 replies, 5 voices, and was last updated 31 August 2015 at 22:32 by steamdave.

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31 August 2015 at 06:06 #7781
Grotto
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@grotto
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31 August 2015 at 06:06 #202576
Grotto
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@grotto
Hi all

I bought a quick change tool post for my ML7 awhile back and just got around to trying to fit it.

It came with 2 stepped spacers, and 1 tubular spacer.
I'm not sure where the spacers go. 1 stepped spacer and the tubular one are too small to go over the tool post bolt on my ML7, 1 stepped spacer fits on the thread of my tool post bolt, but won't fit all the way to the bottom.
Should I drill/ream the tubular spacer to fit my bolt and just use 1 stepped spacer on the top?
Thanks

Edited By Grotto on 31/08/2015 06:15:36
31 August 2015 at 08:46 #202588
John Haine
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@johnhaine32865
One of the stepped spacers goes on the top, and just centralises the block around the stud. There should not be a spacer on the bottom, it would just reduce rigidity and probably make the holder too high. Your first picture shows it mounted correctly, just need to add the nut.
31 August 2015 at 09:29 #202595
mechman48
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@mechman48
The tubular spacer is to fill the gap between the tool post & the stud; you need to have as much rigidity in the assembly as you can get , by fitting the tubular bush/spacer & one of the stepped collars you are, in effect, creating a solid post again. I did the same on my WM250V-F when I changed the 4 way post to a Dickson type QC system, but I machined an all in one full depth stepped sleeve & pressed it in to the block.

George.
31 August 2015 at 09:43 #202598
Grotto
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@grotto
Thanks,

I'll drill out the bush so it fits tightly on the tool post bolt.

I may have a go at making an all in one full depth one.
31 August 2015 at 16:21 #202671
John Haine
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@johnhaine32865
As long as the post is clamped down hard with a stepped washer on top I can't see that an internal sleeve will make any difference to rigidity at all. The cutting forces are mainly downwards. Any radial force will be resisted by the friction between the block and topslide.
31 August 2015 at 20:18 #202712
Michael Gilligan
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@michaelgilligan61133
Posted by John Haine on 31/08/2015 16:21:30:

As long as the post is clamped down hard with a stepped washer on top I can't see that an internal sleeve will make any difference to rigidity at all. The cutting forces are mainly downwards. Any radial force will be resisted by the friction between the block and topslide.

.

+1 for that, John

Unless a bolt is actually "fitted" the advantage is zero.

Incidentally; the [quite unnecessary in this set-up] way to increase available clamping force would be to counterbore the fixing.

MichaelG. [who has done quite a lot of vibration testing]
31 August 2015 at 22:32 #202729
steamdave
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@steamdave
I regretfully succumbed an bought one of these toolholders to replace the GHT 4 way toolpost I had used successfully for quite a while.

One of the problems with the QCTP is that it bears directly on the machined area of the topslide and swarf tends to get under the toolpost. What I have done is to make a top hat washer to closely fit the toolpost hole with the brim about 30 thou thick and of a diameter that is just inside the diagonals of the toolpost (about 2" diameter). The large diameter does not appear to affect the rigidity any and prevents the toolpost marking the topslide. 30thou is of no consequence to tool height setting.

Dave
The Emerald Isle
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