Quick Change Toolpost and Holder systems

Remaining rather off-topic:

I forgot to mention ... Mr. Moseley was a very clever chap, and we owe him a lot.

He devised the Split-Chuck [Collet] and hollow headstock spindle !

... Where would we be without those ?

There is an excellent old book, here, with many references to his designs.

MichaelG.

I decided to go for the nakamura design in the end, but with some adaptations.

Two sets of dovetails and pistons at 90 degrees - so you can switch between facing/turning/boring without losing a setting.

The block is only 2" sqaure to match the square on the mini-lathe top slide. This means the dovestails over lap the top slide, but as you never need to set a tool lower than centre height, this doesn't matter as long as you don't use tools bigger than 5/16".

My pistons are flat ended- to give a line of contact, rather than using rounded ends.

i counterbored the piston holes and used small flanged on the inside of the pistons so they don't fall out - this was not needed as:

I machined a groove inside the central hole level with the middle of the pistons. I drilled the end of each piston No.58 and put a thin spring wire through each one, this locates in the groove and withdraws the pistons without interfering with the cam. I had to filed two bevels on the bottom of the cam so it pushes the cams out of the way.

I fitted a handle that is a longer copy of the standard mini-lathe handles (and the ones fitted to me leadscrew clutch and tailstock lock).

I can't actually test it yet, as I haven't dovetailed any toolholders yet. With about 1.25mm of piston movement I will have to be very careful to get these just right.

I hope it all works, as assembly was a one-way process once the pistons clicked into the cam! To dis-assemble I will need some way to pull the cams outwards -perhaps I should have given them a central 8BA hole?

Neil

Stub

Pictures are required

Hi Chris,

My digital camera plays up if the batteries aren't freshly charged

This is the best I can do with my phone:

Neil

Hi Niel,

I had larger bits vailable so I made my version slightly longer to get the dovetailed bit is outside the top slide surface, I hope it is visible om the picture.

I also intend to mill the top slide surface round like David Fenner did in his article on this subject and hope that I get even more flexibility when it comes to height setting.

Your idea with two dovetails is very good!

Waiting to see your toolholders ...

BR

/Peter

Neil,

Looks good so far.

Edited By Michael Gilligan on 09/09/2012 22:20:07

I bought plans to make a QCTP which is available as a kit (or only drawings) from METAL LATHE in USA, the MLA-23. This seems to be a very nice design, simple and stable. See the following link:

**LINK**

The design is also described in the "Home Shop Machinist" May/June 2006, and also a brilliant description in the "Practical Machinist" forum:

**LINK**

Since I live in Norway, I ordered only the drawings from METAL LATHE, due to the cost of shipping the heavy hardware from USA.

Regards Sverre

Made my first tool holder - I used an aluminium template to make sure the dovetail is a good fit, and of course it is, but that limits the handle's required movement so much I had to drill a new hole for it!

Very pleased that it locks dead solid with only very gentle pressure. I tried it in anger with a 1/8" width parting tool and it seems fine in use.

The holder is are from 1" square bar, and seems to have plenty of metal where its needed.

I am now thinking of all the possibilities and dreading having to machine another nine dovetails

On the plus side, my X2 mill is working much better now it has the added rigidity plate at the back.

Neil

Nice !!

Better picture with first toolholder. Strange colour cast though...

Yes, it is making a stick of height adjustment nuts!

Mighty chuffed with the knurling - 5" of perfect knurl with my home made scissor knurler - my first proper home-made tool.

Neil

That tool holder is looking really good Neil, nicely executed!

BR

/Peter

Don't it always seem the same, you don't know what you've got 'til it's gone... as the song goes.

I got a pile of eight more toolholder blanks, milled out rectangular recesses for the dovetails (would have been a nightmare without my stiffening plate), then put one in the clamping opiece of my knurling tool. and pleased to see the endmill still looked like new at the end.

Got the dovetail cutter out, and finished the dovetail in the knurler and six of the blanks, then almost at the end of the seventh blank, the bloody nylon gear inside the X2 mill went

I've opened it up and it looks like the gear exploded! I can find most of the 20 tooth gear that wasn't engaged, but of the 12-tooth end that was, all I can find are about half of the teeth. They must have completely stripped, before the rest of the gear shattered.

My calculation is that it is 2.25mod, but without atwo teeth side by side to check the cutter against and the thought of having to botch it up on the lathe, I think I might run up the white flag and order a metal replacement on payday.

Had to happen sooner or later - but it's interesting how short the time was once I had the mill rigid enough to start cutting close to its capacity.

Neil

Thanks to this thread I restarted the making of the holders and now I have these:

Ordinary Tool holder

Boring Bar Holder

Threading tool holder Mike Cox style (but I have to invent a solution to the height setting as the current disc will foul the moving part of the holder.)

... and with the tool bit raised

... And they all fit perfectly and is firmly held in place on the post

BR

/Peter

chris j,

I had trouble with rapid - depletion of charge in my camera batteries. I have stopped using rechargeables, now only use non-rechargeables and carry spares if going out somewhere.

Have recently left camera at home and relied on mobile phone`s camera - Samsung GS11 - brilliant quality photos but in fairness to camera, it has more pixels.

John

Just in case anyone wants to build the 'Improved Nakamura' QCTP toolpost design and can't access the back issues of MEW, there's a description of how to make it and a set of toolholders and a download of the plans HERE

Neil

Very generous of you Neil.....

Having read the first instalment of the article I feel the need to make one... Even though I already have a version of a qctp  on my mini lathe.Have to say this one is better....

Thanks again..

Edited By John Rudd on 19/11/2015 21:10:46

Just looked at your link Neil and your page with photo's at Barrs Beacon. I am afraid your a/c recognition is a little dubious. What you think is an Ryanair A320 is actually a 737-800 and the Air France 737 is a Airbus A320.

Thanks, sorted now - I thought I had already sorted it but must have got them muddled.

NEIL