Looking to buy a better toolpost

[JasonBModerator @jasonb]

Just had a measure of my very early model 280 and that only has 23.5mm to play with so there may be a few differences between that, later 280 and 290 lathes

[Cabinet EnforcerParticipant @cabinetenforcer]

There isn't much meat on the topslide to be cutting off, to reduce stack height it is much better to reduce the height of the boss which the topslide bolts to. That's what I did to be able to use the 16 and 20mm toolholders on my boxford size Dickson toolpost.

[petro1headParticipant @petro1head]

Been doing some more measuring.

I have attached a tool holder with a 12mm tool. Made sure the tip is centered.

Looking at the diagram of the wedge

My tool holder size H=8.5mm. The gap from the bottom of the tool holder to the cross slide is 6mm. Total 14.5mm

On the 222 H=12.5. so a couple mm spare

Does that make sence?

The problem with the 111 is it only takes 14mm tools and I have a couple of 16mm boring bars

Edited By petro1head on 06/01/2020 11:11:17

[JasonBModerator @jasonb]

Are your 16mm boring bars actually round, most insert ones have flats.

I have a couple of bigger bars than that and just put the supplied 4-way back on when I use them which is not that often

[petro1headParticipant @petro1head]

16mm Bars have flats so 15mm accross the flats.

I have just priced up the Post including 8 holders, think I may need a lie down

[Tony Pratt 1Participant @tonypratt1]

Posted by petro1head on 06/01/2020 12:47:18:

16mm Bars have flats so 15mm accross the flats.

I have just priced up the Post including 8 holders, think I may need a lie down

Just remember you will only buy the post plus holders once they are not 'consumables'.

Tony

[JasonBModerator @jasonb]

It's all the other holders you buy over time that add up

[Clive FosterParticipant @clivefoster55965]

Posted by John Reese on 05/01/2020 23:58:27:

The Warco style requires the Vs be precisely spaced and parallel for repeatability. I doubt the Asian manufacturers will maintain the level of precision to allow you to buy replacement tool holders that fit properly.

Its a common misconception that Dickson style toolposts and holders need super precise spacing of the Vees to work properly. Line contact of the toolholder on either the two outer faces or the two inner faces of the post Vees is sufficient to ensure stability so small errors of spacing, in grinding machine context at least, don't matter. It is important that they be parallel and of essentially equal depth. Not intrinsically difficult given a sensible production set up. As ever design for production and inherent mutual accuracy from the, ideally simple, set-up is important if precision is to be achieved at a sensible price. The Dickson Vees are good from that aspect.

More likely to get trouble from the locking mechanism. Depending on how you count there are between 7 and 11 places where tolerance errors can build up. Functionally all that matters is that the Tee slot in the holder shall be at the right distance from the toolpost for the tongue to draw the holder hard back against the toolpost when the internal "cam" is close to pullback dead centre. The closer to centre it is the higher the pull back force but if it goes just past force will be lost.

In a practical world thats where errors are most likely to be found. If I had a poorly locking system I'd be playing about with shims temporarily glued on the locking tongue to sort out the actual errors then set about re-making the tongue assembly to functional dimensions. The unit is basically a spindle with a vertical hole through it and a flat end so not hard to make. In principle I see no reason why the tongue couldn't be simply cut off and re-fitted with a countersunk headed allen screw and spacer to get it in the right place. Practice might be a little more challenging.

Took some quick measurements off my size 2 Dickson and Rapid Tipo A posts to get some idea of industrial standards. The Dickson locking handle has 130° total movement giving about 60 thou, 1.5 mm, tongue pull back; call it 0.5 thou, 0.012 mm, per degree. The Rapid has 160° movement giving around 100 thou, 2.5 mm, pull back; call it 0.6 thou, 0.016 mm per degree. Assuming around 10° variation in spindle position at lock is acceptable that suggests something of the order of 4 thou, 0.1 mm, variation in Tee slot position can be coped with. All very handwaving (in the real world there are tangents involved!) but, if it seems like the locking spindle is turning past dead centre, it might well be worth experimenting with a 2 thou, 0.05 mm, shim under the locking tongue. Only good for trials but informative if you do consider re-making the innards. My motley collection of holders from several brands show no readily noticeable variation in locking handle position suggesting that the professional products hold total errors down around the 0.5 thou, 0.01 mm, range when mixed and matched.

Clive

[JasonBModerator @jasonb]

As Clive says it is usually the Tee slot that gives the problems. I posted this photo a while ago where you can see the difference in thickness between the genuine article on the left and another make on the right which stops the cam turning far enough. Cured by sacrificing a woodruff cutter.

The other problem area is where I have the two holders touching in the photo some make contact here first which means the angled faces are not tightly together, this can be cured quite quickly with a linisher or belt sander, milling with carbide should also remove the offending material.

[petro1headParticipant @petro1head]

Posted by Journeyman on 06/01/2020 10:18:58:

There is still about 10mm of top-slide casting left if the boss goes completely but I just reduced the boss diameter to match the stud. Also I used the original clamp lever rather than the nut provided with the tool-post so over clamping is unlikely as no spanner in use. I find the post shows no tendency to rotate even with a relatively light clamp pressure. Unlike Jason I tend to waste time altering things rather than making cracking good models

John

You have mail

[David George 1Participant @davidgeorge1]

Here is a drawing of the original toolholders which fit my Myford Dixon toolpost. The screw hole is used as a datum as a screw with a plane shank is screwed in and all measurements are based about this centre.

I thought to may give someone a base to measure from.

David

[JasonBModerator @jasonb]

David are those sizes taken from an original Weston Engineering "W" holder or from one made at a later date as the size you show is different to what my one in the photo above measures which just goes to show how they vary.

[David George 1Participant @davidgeorge1]

Yes they are from the original that i have and stamped W.

David

[petro1headParticipant @petro1head]

Update

First, thanks for all the input guys.  This forum and its members are great

Got the 222 wedge tool post from Arc yesterday. Fits fine, however ever thought it got two postitions for tool holders only one will fit at a time as trying two one fowls on the other. Aaprt from that very please and soo smooth.

Post to hold the tool post and I have also made a new clamping plate similar to the one John made.

One thing I did notice and hve corrected was the fact the face of the cross slide was not true so have done some machining to true up. This has given me another couple of mm to play with.

Will get some photos posted once my back stops hurting

Edited By petro1head on 10/01/2020 14:46:01

[petro1headParticipant @petro1head]

[Craig BoothParticipant @craigbooth]

Posted by petro1head on 10/01/2020 14:45:13:

Update

First, thanks for all the input guys. This forum and its members are great

Got the 222 wedge tool post from Arc yesterday. Fits fine, however ever thought it got two postitions for tool holders only one will fit at a time as trying two one fowls on the other. Aaprt from that very please and soo smooth.

Post to hold the tool post and I have also made a new clamping plate similar to the one John made.

One thing I did notice and hve corrected was the fact the face of the cross slide was not true so have done some machining to true up. This has given me another couple of mm to play with.

Will get some photos posted once my back stops hurting

Edited By petro1head on 10/01/2020 14:46:01

I have just taken delivery of a WM290V, and am looking for a QCTP. I am looking at the 111 or 222, but I am not sure if the 222 is too big. How are you finding the 222, and if you had to buy again would you buy the 111 or 222.

Thanks,

Craig

[Tony Pratt 1Participant @tonypratt1]

Hi Craig, just sent 2 PM's, I am very happy with my 250-111 size tool post see picture. I took off the solid top slide I had made as per Stefan Gotteswinter & remachined the Warco top slide, much more versatile & rigid enough for big cuts.

Tony

[Craig BoothParticipant @craigbooth]

I see what you've done.In my own mind I was thinking of removing the compound and having a fixed toolpost knowing that I could put back the compound with the existing 4-way toolpost if/when I needed it for taper cutting.

In the back of my mind I am wary of the limitation of the 100 size to 12mm tooling, although I know you can get some 101 XL toolholders that will accept 16mm tooling. Decisions, decisions …

[Tony Pratt 1Participant @tonypratt1]

As you say 'decisions decisions', I use mainly 12 mm carbide insert tooling, plus a tangential tool plus HSS chamfer tools etc. The 12 mm tools will take large cuts with no problem, well as big as 'swarf safety' allows & I did this for a living so not afraid to push the lathe. What's your idea of 16 mm tooling, but in the end neither is wrong or right?

Tony

[Craig BoothParticipant @craigbooth]

The only reason for considering16mm tooling is rigidity. I am only a hobbyist and big cuts are not important to me I just want to consider fully the options before I take the plunge, and not have that nagging doubt later "if only I'd bought …".

I last used a lathe about 40 years ago using HSS so I am not really sure of the capabilities of carbide tooling.

[JGParticipant @jg22384]

This might sound ridiculous but some ordinary writing paper with oil on it might help to keep the toolpost from rotating.. it basically increases the friction between the two metal parts and allows a slightly greater leeway with surface imperfections. It came up on another forum in relation to clamping machine vices.

[Oily RagParticipant @oilyrag]

The wedge toolposts seem to be similar to the Dorian product from the USA. I have several Dorian toolholders and one is very unusual in that it carries the inserted tool in a special front mount 'bracket'. The tool I have is an insert tip for acme threads. I would be interested to see if this would fit one of these wedge type posts.

Toolholder:-

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