Toolposts

I've got a nice Dickson T1 toolpost on my lathe with a slack handful
of toolholders. However I've found that original toolholders are like
rocking horse crap (and slightly more expensive). The replica ones
just don't fit very well.
I was pondering flogging it and buying a piston type one similar to
the 200 model 3/4 of the way down this page.
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least I can then buy (or even make) extra holders that actually
fit.
Anybody have experience of these types? Would it be a good move?
Thanks
Charles
Reply to
Charles Ping
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Bought one off Ketan to go with that C6 lathe, Very well made, mirror finish on the grinding and no matter what holder you use that's supplied it locks at exactly the same place.
The knurling tool holder is a bit naff but it can double up as a spare internal tool holder.
Spare holders aren't too bad at £14.50 but unlike the weird Dickson type these are easier to make. -- Regards,
John Stevenson Nottingham, England.
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Reply to
John Stevenson
Thanks John
The problem that I've found with reproduction "Dickson" toolholders is that the vee on the mounting face isn't suffciently deep to let the tool holder seat properly. The result is that the toggle action doesn't go "overcentre" and under interrupted cuts the toolholder can work loose. I think that I can grind the vee deeper on the surface grinder. Has anyone else encountered the same problem or used a similar solution?
Even if it works I might still get a piston version because the holders are so much easier to make but I'd feel uncomfortable flogging a toolpost with a couple of toolholders that I knew didn't fit properly.
Charles
Reply to
Charles Ping
Charles
Do all the four vee faces make contact with the toolpost? If so, maybe you could consider ways of removing a bit of the inside face of the tee slot. Tricky, I know, but it wouldn't need to be as precise as regrinding the vees.
I made a big batch of holders for my T2 posts a few years ago, in mild steel. I made it in about 16" lengths & sliced them up. Unfortunately I cocked up one length by taking too much off that inside face. It's still kicking around, every time I trip over it I contemplate wheher there's a realistic way to add a bit to that face :-(
Cheers Tim
Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
Reply to
Tim Leech
Tim
I'm not sure if grinding the inside of the tee slot or the vee is easier. The tool to grind the vee is just a normal grinding wheel. To grind inside the tee slot is harder but, as you say, less dimensionally critical. Suggestions for grinding the inside of the vee welcomed.
When you made your batch did you harden them?
Charles
Reply to
Charles Ping
No, just left them 'as milled'. Haven't had any trouble with them, used some for some pretty heavy cuts on the big TOS, and for some deep parting cuts.
I now have to decide what to do when the 17" DSG arrives in place of the TOS. It has a monster 4-way indexing toolpost, I don't want to lose the rigidity which that affords, yet I'm used to the flexibility of the QC post (& I've got all those toolholders!). One idea is to butcher a Dickson QC post & mount one 'face' of it in the 4-way. so I have both options. Later DSGs have their own combined QC/4-way post, it's not a completely novel idea. I don't wish to wreck a perfectly good, expensive, toolpost to do it, though. Anyone got a damaged T2 toolpost, or one of the 2-sided ones off a hydraulic copier? I could do a deal with an undamaged toolpost
Cheers Tim
Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
Reply to
Tim Leech
I mostly make a new toolpost for every tool. Just a simple one from scrap, get a chunk of mild steel about the right size, mill a slot, drill a few holes and tap some of them to hold the tool in place - indexing rotation and position (if the tool needs that) takes two reamed holes and a bit of precision rod.
Then shim the tool in the toolpost to adjust the height - quick and easy if you keep suitable shims handy. To change tool, change the whole toolpost.
When sharpening I don't usually dismantle the tool/toolpost combo - mostly sharpening doesn't affect the tool height enough to matter, so no need to reshim.
I don't know how to get more rigid than this, it's made a huge difference to parting-off large diameter stock - it noticeably improved other things, like turning copper (yeay! :) but the difference in parting-off was not just noticeable, it was a WOW! moment. Rigidity really counts.
I have a small cheap chinese lathe, C3/conquest type, and work a lot in hard material, maybe you wouldn't need the rigidity so much with a better lathe or easier materials - but I have added very firm and rigid topslide, crossslide and carriage locks, and use them a lot. Locking any slides you aren't using is very good for rigidity.
still a newbie, but learning as I go
Reply to
Peter Fairbrother
You're not alone - made the same mistake on a similar batch!
Machined a bit more off. Silver soldered a steel shim in place and remachined to correct dimension. I leave mine unhardened - wear is not really a problem and "soft to hard" grips much better than "hard to hard"
Grinding vees deeper is a bit tricky because the Dickson design is overconstrained and it's difficult to achieve simultaneous bearing on all four vee faces. Patient grinding of the tee slot with cheap little diamond disks would be safer.
In fact it's only the forward vee that does useful location - the back vee does little more than stopping the tool rotating about a vertical axis.
For home brew toolholders it's much better to avoid the overconstraint by replacing the rear vee slot with a simple flat surface that bears on the flat top of the male vee on the toolpost. This avoids the very precise fitting needed with twin vees and makes it a simple weekend job.
I've also made a back toolpost that takes standard Dickson holders. To avoid the overconstraint, the front male vee is machined a part of the solid tool holder but the rear vee is a separate "prism" lighly retained and free to locate within the rear female vee of the toolholder.
Jim
Reply to
pentagrid
Thanks Jim
Since both you and Tim reckon that grinding the inside of the tee is the best way I'll try that with something Dremel like. I'll also have a go at making some holders myself. Anyone know where to get the square headed bolts? - I could use allen heads but they're not as good.
Charles
Reply to
Charles Ping
allen
Charles I have sucessfully softened Dickson tool holders for re-work. I have an excess of the ones with morse taper sockets and use them as the basis for specials. I wrap them in stainless steel heat treatment foil and pop them in my little electric heat treatment furnace. If you put a bit of paper in the foil wrapper to use up most of the oxygen the scaling is minimal. I confess to not bothering usually to re harden and temper but could if necessary.
AWEM
Reply to
Andrew Mawson

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