Taylor Hobson Pantograph Engraver Model D

[jaCK HobsonParticipant @jackhobson50760]

Bodged a std nut, put it all back together, and blow me – it’s better than it was! Hurrah! Before, I tended to move the former or the workpiece on the table rather than use the leadscrew.

[jaCK HobsonParticipant @jackhobson50760]

Bad news for me. http://www.pantograph.co.uk/ don’t have any taper shank adaptors anymore, won’t be getting any more, and couldn’t help tell me the taper angle 🙁

So bodge my own, or ER 11 spindle. Encouraged by my leadscrew bodge, I might have a go at both…

[Michael GilliganParticipant @michaelgilligan61133]

I have just searched through my small collection of Taylor Hobson ‘engraving’ documents, and have found no reference whatsoever to the actual angle of the Trutaper shank 🙁

This de-facto standard remains one of Life’s great mysteries !

MichaelG.

[jaCK HobsonParticipant @jackhobson50760]

I suspect Charles has better skills than me…

I currently can’t measure or machine to that sort of accuracy but from a lot of trial and error, the best fit I can get so far is if I tell my lathe to cut 2.14! I’ll try again ‘fresh’ tomorrow… although I’m running out of 6mm silver steel which I’d hoped to make a cutter from.

 

My engraving attempts so far have poor quality of cut so I really need to improve my sharpening options as I suspect that is a major problem.

[jaCK HobsonParticipant @jackhobson50760]

Yep. Settled on 2.14.

I made a scraper, hone, and reamer so that I could make a brass holder for the engraving cutters. A pleasingly tight fit (didn’t use the hone). A satisfying day’s bodging. I now might have a chance at properly sharpening the cutters. Got to try to make a nut to hold the cutter tight.

 

[jaCK HobsonParticipant @jackhobson50760]

I’m pretty pleased with this spindle body I’ve knocked up out of scrap. Everything is a nice sliding fit individually which tightens up slightly when all fitted together. And the outside dia also a nice sliding fit. Really simple – 2 ‘high quality’ deep groove ball bearings at front and one at back. I suppose one at front and one at back would be more simple 🙂 The front ones take all the axial thrust.

Now a pulley… I go look back in the scrap bin…

[jaCK HobsonParticipant @jackhobson50760]

Wow! I bodged a spindle with +/- 0.02mm runout at the cutter. I don’t know if that is good but I’m going to celebrate.

About £30 in bits (already had scrap metal, screws, and a collet).

[Michael GilliganParticipant @michaelgilligan61133]

Well done, Jack

… I share your joy

MichaelG.

[Andrew CrowParticipant @andrewcrow91475]

Nice work Jack, I think I would be quite delighted with 0.02mm run out.

Andy.

[jaCK HobsonParticipant @jackhobson50760]

Cleaning up now. Seems like there is more swarf than the bits I’ve made.

[jaCK HobsonParticipant @jackhobson50760]

I have come to some conclusions:

I can’t engrave copper with a rotating cutter.

Really small centre drills are not bad engraving cutters… and can be cheap.

.25mm radius tapered fluted ball end cutter is still not fine enough for really small engraving (cutters like used for the desktop CNC engravers).

——————–

I haven’t worked out how to use the quorn for sharpening v bit cutters. In particular, the clearance angle on the leading edge of the V. I’m staring to think I need to make an offset holder with axis 1mm off the quorn hoder axis.

And my Quorn annoys me – The ball end handles need to be done up really tight to clamp effectively. Maybe I just take all apart and make sure there is no oil – but I wonder if anyone has tips for improvement? Might start a new thread for that.

 

[jaCK HobsonParticipant @jackhobson50760]

I have only just realised that is the ‘star of david’. It just happened to be a template that came with the pantograph.

[bernard towersParticipant @bernardtowers37738]

My friends quorn has all the ball handle replaced with socket heads for that vey reason/ and sometimes interference

[Charles JambonParticipant @charlesjambon]

Congratulations on all that you have achieved in a very short time. I am particularly gratified that the 2.14 degree half angle worked for you. I also found it impossible to trace a definitive document from Taylor Hobson or Newing Hall (their successors) specifying the taper so I had to rely on careful measurement of original cutters. The taper angle does look a bit odd and it would be nice to see a round number describing it and, even more, some discussion as to how it was arrived at. The best I can come up with is that it should not be a binding taper while still giving radial stiffness at low clamping force and at 0.9 inch/ft it is 50% more acute than a Jarno and about the same relative to a Morse taper (recognising that this varies for each MT number) so while not entirely self releasing it is not jamming up either.

Regarding sharpening, I use a Newing Hall grinder (there is some related information on the Pantograph Services downloads) for which I had to make the various cams and setting up gauge. But it works fine. I found it was really important to make sure there is a tip rake (rather than a totally sharp point that will almost certainly break off) as well as side clearance. This clearance can be created either by leaving a small land and relieving in a circular manner or by grinding a spiral relief as described using helical cams in the Quorn book or by using a tool and cutter grinding machine relief attachment such as the Alston.

[Author]

Posts