QCTP for 7x Lathe

[ProdEng]

The standard tool post on the C3 is pretty horrible and shimming the tool to height is tedious and wastes time so a QCTP was required. By the time you have a few holders added to the post, buying becomes an expensive affair so I decided to make one. The design is derived from Ralph Pattersons, is easy enough to make and works well. Now that I have one done I will make three more to the same pattern and then some specials to suit inverted parting blade and boring bars. This was the first time I wrote out the machining process and followed it ! Organistion speeds up the work

 

[steamer]

Nice Job Jan!

That's a very old design orignally known as a "Norman Patent" design around the turn of the century. Just as good today as it was then!

Dave

 

[ProdEng]

Thanks Dave, I didn't realise it was such an old design. I wanted a compact toolpost as there is so little room on these small machines. The toolpost seems rigid enough, certainly better than the original item.

Jan

 

[steamer]

Hey Jan,

Check out a little past mid page of this link.....interesting read

http://www.lathes.co.uk/waltham/index.html

Dave

 

[lazylathe]

Nice one Jan!

To me it looks like it is a complete unit, no dovetail to remove the holder.
Dave found the exact unit you replicated! Go Dave!

Looks like a nice solid tool post.
Easier to make than having to deal with dovetails!

Andrew

 

[ProdEng]

Dave, an interesting read indeed and shows how little there is in the world that can be called new. I love industrial history having grown up in the English Midlands, the heart of the now sadly gone engineering industry.

Andrew, the toolpost is pretty straightforward to make but needs a very good fit between post and holder to work at its best. The one I made has about .001" interference and the holder was lapped onto the post to get it to move a bit more freely. Very little pressure is needed on the clamp bolt to lock it up solid.

Jan

 

[steamer]

I didn't look that hard....the photo's of the Waltham lathe on Tony's site are of my own Waltham....

Dave

 

[ProdEng]

Four toolholders are now complete, making parts in batches sure does speed things up. The parting blade does not fit this holder design very well so I decided to make a separate post for it instead. Work has started on on the parting holder and I will post some pics when there is something worth looking at I have yet to decide how the boring bar system will work and will return to it after the current job is complete.

Jan

 

[bp]

Hi Jan,
When I made my QCTP more or less to the same design as yours, I turned the parting blade upside down, and part off with the spindle in reverse....magic!! No more parting off probs.
cheers
Bill Pudney

 

[ProdEng]

Thanks for sharing your pics Bill, that's a very elegant solution to the problem. I particularly like the clamp arrangement for the blade. Is your toopost mounted on the top slide or the cross slide ? It looks quite deep so I am guessing the cross slide. Your parting blade profile also looks interesting; who is the manufacturer of that ?

Parting off in reverse is a benefit of a bolt on chuck, I sometimes turn in reverse when access is a problem.

Jan

 

[steamer]

Hey Jan,

I think a straight forward bored block would work well for a boring bar holder...make it for your largest boring bar and then use split bushes to hold the smaller boring bars.....otherwise make a set of holders...

Dave

 

[ProdEng]

I think you have the answer Dave, problem solved! As I am only making little things my bars only need to reach about 2 inches and the biggest bar would be 3/8". Come to think of it, they can all be made from 3/8" stock with the business end turned down to suit, save on making bushes. A 4" length of 3/8" stock is pretty cheap and a set of three should cover most jobs. For longer bores or bigger diameters I can always line bore as I have a tooling plate for my cross slide.

Jan

 

[steamer]

If you make up your QC block, mount it on the post, and drill/bore the block right on the lathe.

Dave

 

[bp]

My post is 35mm diameter, and its mounted on the compound slide. It was intended to reduce any overhang as much as possible.
The part off blade comes from LMS and is by A. R. Warner, I use the 1/32" and 1/16" blades an they work very well.
I've attached some more photos.
cheers
bp

 

[bp]

Sorry, this is the picture I mean't to add.
cheers
bp

 

[ProdEng]

Thanks for the additional pics, makes things a bit clearer. Must order some of those blades

Jan