Lorch lathe toolpost base dimensions?

[Betzel]

Greetings,

If anyone out there has an older Lorch toolpost with the eccentric holder for 4mm tooling, I am making a base or holder support and need just a few dimensions. I can guess at these, but would appreciate being close to the original. It's the OD, max/min base heights and cutout width that would be helpful. Hope you can see these arrows?

 

[wefalck]

OK, pulled out my set - I not normally use it anymore since I made myself a QCTP some 20 years ago.

I enclose a couple of pictures of the complete arrangement:





From the bottom you have a knurled, wedge-shaped washer, then the support plate for the the bit. Then there are two options:

- for a square (5 mm x 5 mm) bit, you use the flat side of the support plate up and the kind of half-round part with the dimple on top of the bit to disstribute the pressure

- for larger round bits (up to 7.5 mm bit diameter), you can use the support plate with the groove up and again use the half-round part to distribute the pressure

- normally you would use round 4 mm (boring) bits, for which there is a special excentric holder; the holder is slotted and has a cross-hole to fit the bar with which you normally lock the the longitudinal slide; with this you can turn the excentric holder to adjust the cutting edge; to distribute the pressure from the screw, there is a special piece with a matching groove.

The knurled, wedge-shape washer mainly serves to adjust the height of the cutting edge of square toolbits and may not be needed when using the excentric holder for round bits.

To answer your specific questions:

- the support-plate has a diameter of 19.7 mm and is 4 mm thick; the groove has a radius of 3.5 mm and is 1.5 mm deep
- the knurled washer has a diameter of 20 mm and its thickness varies from 1 mm to 2 mm
- the bore in both parts is 10.8 mm, which obviously is the diameter of the toolholder
- the slot in the toolholder is 5 mm wide
- the body of the excentric toolholder has a diameter of 7 mm and diameter of the bulbous end is 11 mm, the overall length being 40 mm.

Hope this helps. Feel free to ask for more dimensions, if needed.

 

[Betzel]

Hope this helps.

Absolutely! A QCTP would be nice --someday.

I recently found an eccentric holder, boring bar and the matching grooved piece at a low cost. So, I just want to try the boring bar on my Wolf, Jahn slide. I think the W-J and Lorch parts I have cobbled together were similar. I have always wondered what all those other small parts were for. Now, I know!

Thank you for the very thoughtful and thorough reply!

 

[Betzel]

It finally warmed up enough for me to brave the shop again so I made the part. Thanks again to wefalck.

I thought these setups were made only for Lorch and Wolf Jahn lathe sets. Turns out mine is different. This "offset" holder for the 4mm bar is 7.95 in diameter and 48.25 long, so a little fatter and a lot longer. I once saw one of these in a boxed set of B&L reform accessories, so maybe its from one of those? Don't know. Anyway, it works (??) with what I have, but differs from the above dimensions because of all that.

I've never cut an ID before. So with the offset neutral, and the cutter flat, I am about at the center. If OD turning should cut on the center line, would the same be true for ID / boring work? Many thanks if you can advise!

 

[wefalck]

The same principles applied inside and outside re. cutting angles, tool-height etc. These tool-posts were meant for boring bars ground like D-bits. They were supplied readily ground with different diameters at the end for e.g. jewel setting. I have a bunch of them that came with my Wolf, Jahn & Co. outfit. The square front means that you have a flat bottom, when you don't bore through.

Personally, I prefer these days single-lip carbide end-mills for boring. They work on any kind of material. The D-bits have a zero cutting angle and, hence, are only good for brass.

Blued parts seem to be more common on Boley or Boley-Leinen equipment, so yours may well come from one. On the other hand, the non-metric dimensions point to some anglo-saxon origin.

 

[Betzel]

Thanks.

I think zero means "neutral" rake, like I do for drill bits for brass. I will try it. Did not know they supplied so many options! Once made a cutter out of 4mm steel, drilled to hold a reshaped piece from a broken carbide drill bit cross-wise, but I don't think this was a single lip cutter. I will search around to see what those look like.

All my parts are cobbled together, but it's mostly Wolf Jahn. When the plating goes bad I take it all off and blue. The larger pieces are a challenge.

 

[buchnoun]

OK, pulled out my set - I not normally use it anymore since I made myself a QCTP some 20 years ago.

Hi,
I'll be interested to see your QCTP. I've just bought a § and a 8mm Lorch Lathes and I'd like to be able to adjust the height of my tool in a more convenient way : on my TP I need to put shim under the tool holder to raise it... not practical
Any ideas welcome to find a better solution
thank you

 

[wefalck]

You can have a look here: Attachments

You will have to have a milling machine to make one though ... there are also some Far East ones popping up on ebay etc. from time to time.

GG-Tools in Germany also have one: http://gg-tools.com/epages/4a53cb12-c349-4e1e-aa61-062b1756241c.sf/de_DE/?ObjectID=5016426. Mr. Gottwaldt has also an ebay-shop, but I don't know, whether he lists there this one. He does speak English, I think.

 

[buchnoun]

Thanks for your help. I was wondering if those asian QCTP were compatible with my cross slide and I'm happy to get some measurements from your files
Thanks again

 

[Betzel]

If you measure up from the platform top of your slide, and add the thickness of the bottom of a holder to the 5mm blank (assuming Lorch or Wolf-Jahn sized tooling) and the top of that 5mm tool blank still leaves you 1mm or so to the tip of the dead center point, you should (?) be able to use one of the asian kits. There was a guy in singapore (taylor or simon or something?) who was making one that looked reasonable.

Not as much fun as doing it all yourself though

 

[wefalck]

I haven't seen the one from GG-Tolls in real life, but he writes that it is suitable for the usual watchmakers lathes.