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Member postings for Mike Donnerstag

Here is a list of all the postings Mike Donnerstag has made in our forums. Click on a thread name to jump to the thread.

Thread: Any other bowmakers on here?
15/10/2019 22:54:15

I wondered whether anyone in the Lincoln area might be going to Midlands Model Engineering Exhibition at the Warwickshire Event centres this weekend and perhaps fancied doing a car share?

Thread: Myford Vice for Vertical Slide
22/09/2019 17:07:49

If any of you were to buy a machine vice for the Myford milling slide from ArcEuro (I have a 10% discount code), which one and what size would you buy?

Many thanks,


Thread: Knurling wheels (for the Hemingway Sensitive Knurling Tool)
28/08/2019 16:07:36

It’s a good idea, but a 45deg diagonal rotated 180deg is still (the equivalent of) a 45deg diagonal.

It’s like looking at the following upside down:




28/08/2019 15:13:24

I recently made the Hemingway Sensitive Knurling Tool, which is designed around knurling wheels that are 5/8" diameter and 3/16" thick with a 1/4" bore.

I picked up a pair of Jones & Shipman diagonal-knurl wheels from eBay recently, which I had assumed would give me a diamond pattern knurl. Unfortunately it was only after receiving them that I realised that both of the wheels were diagonal in the same direction, resulting in a knurl that simply looks like a multi-start thread!

My question are as follows:

Q: Would anyone need or want a knurl like this on a part?

Q: Can I obtain a single Jones & Shipman knurl of the opposite direction? If so, can anyone suggest a supplier?

Many thanks,


Thread: Myford ML7 tailstock bore, and threading the barrel to fit a chuck
23/08/2019 20:21:55

Bill: That's a good idea, though most woodturning chucks don't tend to come with jaws that are able to grip an octagon (bow sticks are octagonal - another problem to overcome!). I've actually been woodturning for many years and have a similar chuck (the old Multistar Titan), but the accuracy is questionable. They also tend to be large (mine is smaller than most, at 3".

23/08/2019 18:31:12

Many thanks for your message Cornish Jack, but yes I'm afraid you missed something, or more likely I didn't explain very well. I'm using an ML7 tailstock as I need to pass the bow stick all the way through. Using a morse taper chuck carrier as you suggested means that the benefit of the hollow tailstock is lost. It's not an easy problem to solve but I think I'm slowly getting somewhere...

I've purchased an ML7 tailstock (£74 for a Mk2 from eBay) and a tailstock lever (cheapest was £92 from eBay) that will be needed instead of the normal rotating handle. I've worked out, based on the worst case, a cello bow, that the maximum length of the fixture from chuck jaw to the end of the barrel is 250mm. To make this work I think I'll need to do the following:

  1. Shorten the front of the barrel
  2. Shorten the nose of the tailstock
  3. Buy a short chuck and turn a backplate that will be secured (probably loctited) onto the tailstock barrel
  4. Cut a notch out of the back of the barrel to accommodate the bent instrument (violin/viola/cello) bow stick

The objective is to result in a fixture that I can easily and accurately remove and reattach to the bed whenever necessary, without any wasted settting-up time. I will need a minimum of 20mm of travel on the barrel, which is significantly less than the original (approx.) 80mm.


Edited By Mike Donnerstag on 23/08/2019 18:46:23

23/08/2019 14:08:54

What do people think about boring the back of a small four-jaw chuck to fit onto the tailstock barrel, and fitting grub screws to lock it, and possibly adjust the concentricity? That would save some length otherwise taken by a backplate. Keeping the assembly as short as possible reduces the amount of bend in the violin bow that the barrel would need to accommodate.

To this end, would it be possible to machine the jaws of a chuck to reduce the protrusion? How hard are chuck jaws? The chuck I was thinking about is the 60mm Indian chuck supplied by Arc Euro:

Does anyone know of an alternative, ideally shorter, self-centring 4-jaw chuck?

Once again, any help gratefully received!


Thread: Meddings Driltru Handwheel (Star Wheel) Stiff
23/08/2019 14:00:36

Just for interest, I reamed the bush very lightly from both sides, polished the spindle (it was lightly scored) and reassembled. This improved the problem. Once the weather had cooled down, the problem went away altogether, which definitely points to the fact that the nylon bush is tightening onto the spindle when the weather is hot.

I hope that helps anyone with a similar problem.


25/07/2019 17:54:25

Bikepete: Did this work without creating too much play?

Thread: Meddings pillar drill problem
25/07/2019 17:41:32

I have the same problem with my Meddings Driltru. Having dismantled the quill, etc., the tightness is definitely due to friction from the plastic bush on the activating gear shaft.

Roger: Did you find a solution to this?


Edited By Mike Donnerstag on 25/07/2019 17:53:43

Thread: Meddings Driltru Handwheel (Star Wheel) Stiff
25/07/2019 17:34:28

I have a Meddings Driltru floor-standing pillar drill. I've noticed that the quill becomes more difficult to move when the weather is hot (such as today!). As I do a lot of work with small drills, this is causing a problem!

Having removed the handwheel, spring and shaft, as well as the quill assembly, I found that the problem is the plastic (nylon?) bush that the handwheel shaft runs through. I have removed the 2BA grub screw under the bush that, I assume, sets the tightness of the bush on the shaft.

In the parts diagram, the plastic bush is labelled 15 - Activating Gear Bush, and the shaft is labelled 13 - Activating Gear and Shaft Sub-Assembly.

My question is, what can I do to make the shaft run smoothly? The shaft is 5/8" in diameter. Should I run a 5/8" reamer down the bush?

Many thanks,


Thread: Solving Engineering Mistakes
24/07/2019 09:07:31

I knew you fellas wouldn't let me down!

AdrianR: Why didn't I think about reducing the overall thickness of the side piece, and thereby reducing the over-milled step? That's exactly what I'm going to do, so many thanks! That way I'm not affecting any of the other (correctly sized) components. If anything goes wrong, I'll just re-make that side piece. (Did I say 'just'??)

The side piece that is a close fit supports the knurling tool when it traverses towards the headstock, it's only when it traverses towards the tailstock that it is not so well supported, due to the over-milled side piece.

Anyway, there are some great tips here. All the books explain how things 'should be done', but the real skill seems to be in solving or at least working around these mistakes. It reminds me of articles I've read in Fine Woodworking in the past on how to solve common woodworking mistakes. (Neil: I have the PDF articles if you're interested, though I realise of course that metal is a very different material to wood. It helps that a glued wood joint, if done well, is as strong, if not stronger, than the wood itself.)

Once again, many thanks!

22/07/2019 13:58:50

One idea was to sweat a thin piece of mild steel onto the piece using silver solder, or perhaps even 'glue' a piece on using loctite? I assume that 20thou isn't a thick enough piece to hold in place using any kind of countersunk screw. Ideally, the solution would not show on the outside of the tool.

John: The knurling tool seems to work okay, traversing in both directions without excessive play in the arms, so you may well be right that I can leave it 'as is'. As the tool is near to being finished, it's too late to change the dimensions of any other pieces. If I were to use a brass washer or thin sheet, how should I fix it to the component?

22/07/2019 10:05:09

I'm sure this is a beginner's question: I've been making the Hemingway Sensitive Knurling Tool, as in the picture below:

hemingway sensitive knurling tool.jpg

As a rookie engineer, I made several mistakes in the making, mainly during the use of the Myford Super 7 for the milling operations. Specifically, I machined the side plate step 20thou too deep. This surface of this milled step is 2" x 7/8". My question is, rather than scrap the part and re-make it, can I 'add' a piece 20thou thick to this surface in some way?

I also wondered whether anyone had any other tips for solving common engineering mistakes, at least for non-critical parts that aren't under any strain.

Many thanks,


Thread: Myford ML7 tailstock bore, and threading the barrel to fit a chuck
17/07/2019 15:44:57

Yep - Thanks DC31k. That is all the information I should need to see if this is practical.

Many thanks all,


15/07/2019 19:19:04

Also, can anyone tell me the maximum travel of the ML7 barrel?

Thread: Any other bowmakers on here?
15/07/2019 18:58:23

Neil: I wondered who that guitarist was and had to ask my muso friend - of course it's Rory Gallagher.

Roderick: That's really interesting that you've made bows. I'm in touch with John Stagg, who recently retired from bowmaking due to ill health, but has never made baroque bows. Your bow looks really good. I have never even heard of Beefwood, but will do some research. I wonder whether it's anything like ironwood?

I would really be interested in your view of a stick drilling jig based on an ML7 hollow tailstock. The thread is here:

Many thanks,


Thread: Myford ML7 tailstock bore, and threading the barrel to fit a chuck
15/07/2019 18:46:16

MichaelG/DC31k: I really like the idea of the clamp-on mounting that can be removed. Even if a register is loctited on and a thread cut into the barrel, it would still function as a tailstock, albeit with a limited movement.

Howard Lewis: I think you mean the one Harold Hall published. It's on his website: - certainly a possibility, though I'd still need that thread and register at the tailstock.

Can anyone tell me the overall length of the ML7 tailstock barrel? I'm asking because even though the butt end of a violin bow is straight, it is only straight for a certain length before the curve starts (known as the camber). It could be that the tailstock barrel might foul the bow stick due to its length. (Nothing is ever easy is it!)


Edited By Mike Donnerstag on 15/07/2019 18:48:26

Thread: Myford Vice for Vertical Slide
15/07/2019 18:35:14

Does anyone use a swivel vice with the Myford vertical milling slide such as this one:

groz 3-way swivel vice.jpg

15/07/2019 14:54:24

Another view of my vice, showing the part number:


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