Lathe mounted slotting attachment

[Spurry]

In order that I can avoid the possibility of arrest for Cruelty to Lathes,    (see the vice speed handle thread), to make any future square holes or keyways I thought it best to make a proper slotting attachment, instead of using the lathe carriage.

I have found an old toolpost that I made for a large? 22mm boring bar. Just fits in place of the QCToolholder. A thought passed through my mind that this could be a good basis for a slotter, with the ram on one side and a pivot on the other.

Looking round the internet there seem to be many variations on a theme. One I looked at, even had what appeared to be four pivoting links, so not quite sure how that worked in practice.
Has anyone any tips or advice especially handle/ram ratio and placements of pivot points. I am looking at mounting a 22mm ram in a 100mm long x 60mm square of cast iron bar mounted in one side of the toolpost. (Size chosen as I have a 22.00 reamer.  )

The toolpost is 75mm square with a 12.00 central hole and is 50mm tall. The old boring bar sat at lathe centre height, (in the rusty bit.)

TIA
Pete

[DavidA]

Just wondering how the assembly will stand up to the rather jarring action of the cutter being used. Won't it tend to try and rotate around it's central bolt ?

Dave.

[Spurry]

Thanks Dave, I had wondered that too. On the QC toolpost there is a pin that locates the block in line with the top slide. With some careful measuring I could add such a pin to this toolpost, but not sure if in it's design it was meant to resist possible turning motion, or just as a locator for squareness. 
Pete

[mexican jon]

I'm not at home so can't take a picture of mine  but it is based around this 1 which I found on the net  it uses an original top slide but is similar in design as to your thinking 

[Pete.]

Just wondering how the assembly will stand up to the rather jarring action of the cutter being used. Won't it tend to try and rotate around it's central bolt ?

Dave.

Can't see it being a problem. Cutting a few thou deep every stroke doesn't require much force.

[BaronJ]

Hi Guys,

I thought that you might like to see mine.  I built it to put keyways into bronze gear bores.  It is built to fit directly onto the Myford QCTP.

[jcs0001]

Neat project - I will be watching.

If you could reduce the distance from the mounting point of the toolpost (the bolt through the centre) to the sloter ram, it would reduce the amount of torque when using the slotter.   Not sure if that's needed but just my $.01.

John.

[Spurry]

Thanks for the interest. 

Baron - could I ask what the total ram travel is, distance between the centres of pivot and the handle, and length of handle. Is the ratio about right for the amount of effort needed?

Pete/Dave, I cannot fit the pin as it would go through the slot corner. However the top-slide itself is 76.18mm wide, so would be a simple matter to add a restraining bar on one, or both sides of the actual toolholder, to prevent it from pivoting...... should it be necessary.

The ram will have to go on the inside slot of the toolholder, as the cross-slide runs out of travel before the ram would get anywhere near centre if it was on the outside. I was hoping it would fit the other way round.

Pete

[DavidA]

Pete,

Yes, some kind of retaining bar/block should do the trick.

Baron,

I like it. Must add that to my to-make list.

Dave.

[RobWilson]

Evening Pete


This be my lathe slotting attachment , cuts a 1/4 keyway in steel no bother,thats not to say it will not cut larger ,its just the larges I have cut with it .






Stainless steel steering wheel boss splines .




Cast iron gear






File attached ,scale as required 


Rob

[mexican jon]

Rob that is some impressive work there 

[PekkaNF]

Those slotting gadgets are interesting and many of them seem to ownd design to graduating tool.

This type:
http://www.hemingwaykits.com/acatalog/Keyway_Slotting_Attachment.html
http://s1247.photobucket.com/user/don1966/media/KEYWAY%20SLOTTING%20ATTACHMENT/IMG_1750_zps515a6f0e.jpg.html
http://mikesworkshop.weebly.com/toolpost-slotting-tool.html

There is some designs build to tail stock, much like lever drilling feed, can't rememeber maker.
This one was used for drilling, but looks strong enough for slotting
http://www.bikepete.f2s.com/pics/hardinge-tailstock03.jpg

Some years back I read about one clever design that moved the whole big slide assembly (to avoid rocking of the tool post type thing when you hang on the loever), arms were pretty long on that one. I liked the design, but after reading descrioton I bought a set of standard keyway broaches and later a hydraulic press.

Still thinkking of making a gradutaing tool, possbly stong enough to make those nonstandard keyways...

Pekka

[Spurry]

That's a lovely bit of gear Rob.    Thanks for the link too. Have you kept to the pivot ratios as per the drawing?

Pekka. We must move in similar circles.  The first one I looked at was the Hemingway one, but thought it very expensive. I had looked at Mikes one too. That one gave me the idea of using the old toolpost. The tailstock one looks interesting, but I was hoping to save a bit of work. That's probably the strongest setup though.

Thanks again to All, for the hints and tips.

Pete

[RobWilson]

 His Pete

Mine is built exactly to the drawing no changes . It's a well designed tool. 


Rob

[Spurry]

......built exactly to the drawing no changes . It's a well designed tool. 

Rob

Mmm. Not quite, your handle is much more posh than the original, for a start.  . I had forgotten all about that item in the issue of MEW from 1991. Pity it did not even make it onto the front page.

Having translated some of those dimensions to metric, there is only 1.38mm between the edge of the main mounting hole and the edge of the ram bore, whereas in my initial thoughts, mine was looking at somewhere around 40mm. As has been pointed out, this could cause a problem.... back to the drawing board.

Pete

[BaronJ]

Thanks for the interest. 

Baron - could I ask what the total ram travel is, distance between the centres of pivot and the handle, and length of handle. Is the ratio about right for the amount of effort needed?

Pete

Hi pete,

From memory without having to go into the workshop tonight. 

The travel is about 1" (25mm)  The handle to pivot ratio is 12.  FWIW the ram was made from an old pulley key, machined to give a square section and the end drilled to take the tool bit with a 1/4" BSF allen grubscrew to hold it in place.  The body is made from a tool holder that fits into the QCTP.  The brass adjusting screw was fitted to remove any play whilst giving free movement.

Note that the ram runs on thin brass (0.4mm thick) strips inserted top and bottom.  This prevents steel on steel galling under pressure.  The handle is a 13" length of silver steel with a heat shrink hand grip.

I have some pictures of its construction if you want to see its bits.

[Spurry]

Hi Baron
Thanks for the info. I have already ordered some stuff for my original design, some of which arrived today. A piece of cast iron bar 60mm sq x 150mm and 4 pivot bolts. I await the 22mm silver steel for the ram. Currently trying to rearrange things to suit a new design, a bit in line with the one Rob shows above.
Thanks again
Pete

[Spurry]

The new design will be based loosely on Rob W's slotter from the original MEW article from 1991.
Main difference will be no casting used. (CES appear bashful about price and availability of stock.) Their casting is designed to be fitted to the cross slide, whereas I prefer the top slide placement.
Main disadvantage of mine is that I cannot have the ram and pivot points on opposite sides of the main retaining stud, as the cross slide runs off it's thread.
Some sizes have been altered for material I had in stock. The pivots will utilise allen headed shoulder bolts.
A start has been made on the handle, and pivot links so far. The two sets of pivot links were drilled and reamed separately using DRO, fitted with the bolts to confirm accuracy.
Pete

[John Rudd]

Looks good Pete, I did look at the casting on CES, but like you couldnt see the price....annoying really!
I would  have suggested it but for that reason.....I have one on my list somewhere.... the casting is currently wrapped in newsprint under the bench....

[Spurry]

Looks good Pete, I did look at the casting on CES, but like you couldnt see the price....annoying really!

Thanks John. I got as far as sending them a price-request email. A second email requesting the last price it sold for, goes unanswered. I also asked for the units mentioned under cast iron bar, no response on that either. You can select 1 or more units, but no mention of what - mm, cm, inch, foot, yard or metre.
Pete

[John Rudd]

So, all in all pretty helpful?....not!
They were so much better before they were taken over/ sold on.....

I emailed them not long since for some cast iron billet, got a reply, phoned them up and got it delivered almost two days later...service was great...not now tho'.....

[stvy]

Hi,

This is an interesting project. So I rang CES and they told me that this casting (and a few of the others you can't currently add to your basket on the website) are out of stock and the foundry should deliver in January 2017.

I also asked about getting a bit more stock on it for increasing the center height. I need 76mm + some machining allowance up from the stated 52.4mm if I put it on the top slide. I don't have a t slotted cross slide so I think the top slide is a better compromise. He was none committal and suggested I put it in an email. I have a between centers boring bar but the minimum size it can bore is 13/16", so I should either upscale the whole casting or have to make another between centers boring bar.......  So I conclude no casting for me  , instead I need to buy a block of cast iron.

Regards,
Steve

[Spurry]

Steve
I got my block of cast 60mm x 60mm from a chap on EB. His name can be PM'ed if required. I don't know if we are allowed links in public here.
The ram on mine will be 22mm, so slightly upscaled from the original.
Pete

[krv3000]

I have seen rob's up close and its as good as the pics its like tool porn im on making one but mine is fitting in the tool post as my lathe is only a liltel one 

[Spurry]

Some slight progress.
1. Parted off the handle, drilled 12mm. Turned a 12mm spigot on the 1" x 1/2".
2. Two parts fitted.
3. Following being attacked with the mig welder.
4. Cleaned up with roll sander.
5. Roll sander
6. Poor mans surface grinder? (with the roll)
7. Finished effort. Just got a slight undercut where the weld started/finish on the 1" x 1/2".  Any ideas how to avoid that?

Pete