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Member postings for old mart

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

Thread: Stripped thread / Pultra P type
24/10/2019 23:00:51

Unfortunately, the wall thickness of your nuts is too thin for simply replacing the thread by bushing, I think the complete nut assembly will have to be replaced. The pictures do not enable a guess at the actual size of the thread. What is the thread pitch, there seems to be a choice of 1mm, 40 tpi or 20 tpi.

Thread: portable LED floodlight , power source ?
24/10/2019 22:15:59

Lidl have recently had two of these for sale, one battery and one mains, I bought the mains one, it was £14.99, I think the battery one was more. The mains one has 1500 lumens@ 20W and is intended for a security light, it comes with a remote control programmer. I intend to use it as a light for the mill, on an adjustable arm.

Those 18650 lithium cells are easy to get hold of if you need some.

Edited By old mart on 24/10/2019 22:18:34

Thread: Replacing a Clarkson 'autolock' chuck with a standard ER collet chuck?
24/10/2019 21:04:11

For potential fitting of a Myford backplate onto the spindle, there is a shoulder just below the spanner flats. You could make a tubular collar for the backplate to tighten onto. Unfortunately the backplate will have to be machined in situ on the mill for it to run true, an easy job if you think of a vertical lathe and hold a lathe tool in the milling vise. Expecting the backplate/ collet chuck to run true if you were to fit it on the lathe is very long odds against. The mill and the lathe would each have to have their own backplates, but could share the collet plate.

I bought a 9" faceplate on ebay very cheap, for the Smart & Brown model A. I knew what it was by the casting number on the rear. I cleaned everything and set up a tool to skim it on the lathe, and something got into my head that I should check it first. It ran 0.0005" tir, so the skim was cancelled.

The RDG collet chuck and backplate is a very good buy, and as mentioned, more compact than my link.

The Tom Senior Light Vertical mill which we have been working on has been converted from MT2 to R8, it came with their version of a Clarkson Autolock for screwed shank tooling, it has a threaded collar at the top which is tightened against the end of the spindle. This stiffens up the rather flexible MT2. I wasn't happy to use MT2 which was why I converted it to R8, also to use all the R8 tooling that we have.

Edited By old mart on 24/10/2019 21:22:33

24/10/2019 19:38:07

That peak 4 suggestion sounds promising regarding the spindle nose threads.


As for the lack of enough metal in that collet holder, it is the only one I could measure. There may be others with greater lengths, but it would be a lottery whether they would work, I will see if my R8 ones have that 0.733" bore in them.

Edited By old mart on 24/10/2019 19:45:48

Thread: Pratt Burnerd 4 jaw Chuck jaw alignment
24/10/2019 19:16:36

I set up one of the jaws of my Toolmex light 6" chuck, which is in almost new condition in a similar fashion except for having a cylindrical surface for the tip to bear against. The ground surface if the jaw tip is not flat, it has a radius. The jaw is exactly 16mm wide, so I used the shank of a 16mm endmill. The measured slope is much less than yours at 0.0005", 0.0127mm over approximately 40% of the length of your jaw.

Thread: Replacing a Clarkson 'autolock' chuck with a standard ER collet chuck?
24/10/2019 18:52:58

I have some dimensions of the MT2 er25 collet holder that I have. It is one of the cheap Chinese ones from ebay. The 0.7" large end could be compared with that same diameter on your Clarkson to get a reasonable idea of how deep it will seat. There is some scope for adding flats, although the milling might require carbide cutters. I used solid carbide endmills to put spanner flats on both of the R8 er25 collet holders that I bought before it was common to include the flats from new.


Edited By old mart on 24/10/2019 19:00:03

Thread: Those little screws for carbide inserts...
23/10/2019 21:25:07

The forces on the insert are mostly down through the toolholder, as mentioned, the screw does not have to be super tight or strong. It is more important to ensure there is no swarf stuck between the insert and the toolholder when it is fitted. I do, however, have a Ceratizit shell mill with 5 round inserts which is rated for 11000 rpm. It stresses that if the maximum speed is used, then the screws are changed at the same time as the inserts, which can index 8 places before discarding.

Thread: ww2 jeeps
23/10/2019 20:59:57

It looks like a miniature version of a DUKW

Thread: Hi all
23/10/2019 20:51:11

Hi Jerry, there will be lots of old vehicle buffs on this forum, lets hope the workshop has some nice tools in it.

Thread: Replacing a Clarkson 'autolock' chuck with a standard ER collet chuck?
23/10/2019 20:25:42

Too much bother, you could sell the Clarkson and get a MT2 er25 which goes to 16mm. It should not need the locking flats. Only buying one and fitting it will allow you to find out if it is viable. It wouldn't cost much to prove it one way or the other:


 I have an er25 MT2 which I could measure to give some idea if adding those drive flats would be feasible, but it is difficult to judge exactly how deep the tool goes into the spindle. Hopefully, I will remember to measure it tomorrow (Thursday).                                                                                                                                                                          Your Autolock is a rare bird, and may have been made in this form just for that one make/ type of mill.

Edited By old mart on 23/10/2019 20:42:01

Edited By old mart on 23/10/2019 20:44:34

Thread: Pratt Burnerd 4 jaw Chuck jaw alignment
23/10/2019 20:13:54

Making a four leaf clover tensioner seems like so much bother, and it only fits one size of jaw. That's why I drilled the jaws with a carbide drill and use any of several rings of different sizes bought cheaply on ebay. The rings are primarily for use with the serrated jaw chuck which requires tensioning every time the jaws are bored.

Thread: Packed Boring Bars
23/10/2019 20:05:36

Most of mine are solid carbide or densimet. I have only ever bought one, a Garant 6mm, but it cost a lot for a box of inserts as they are tiny proprietary ones. Don't think that a top quality steel boring bar is any less bendy than a cheap one, size for size,Youngs modulus for steel doesn't vary much.

Thread: Reaming a large diameter by hand
23/10/2019 19:55:28

It is difficult to get a good finish with any straight flute reamer, let alone an adjustable one. You will likely end up with a bellmouthed hole. I would go for a different approach, namely, boring the bush to finished size, and making it a sliding fit in the housing, (0.001" clearance), and using Loctite, 601, 638, 620 or equivalent.

Edited By old mart on 23/10/2019 19:56:50

Thread: Boring head
23/10/2019 19:47:20

Go for the larger one, you are unlikely to ever buy another. The cutters are not much cop, but they can be improved somewhat by touching them up with a diamond hone. I have turned the centre part of each cutter shank a few thou down so the burr left by the securing screws does not make them difficult to remove from the head. As the head will be out of balance, use a fairly slow speed.

 Never run one of these in reverse,it will unscrew from the arbor.

Edited By old mart on 23/10/2019 19:49:17

Thread: Gandalf is broken
22/10/2019 20:32:51

Get one like this, she won't be able to knock it over.laugh


Thread: What is this thread called these days? 3/4"-16 SAE
22/10/2019 20:27:57

Thee were some changes made when UNF was ratified, that 12/14 tpi was exactly where the change took place. UNF threads from 1" upwards are now fixed at 12tpi, unless they are UNS, which could be anything.

22/10/2019 16:54:07

Also threads marked NF are now UNF.

Thread: Two weeks wasted
22/10/2019 16:52:07

Check out the list of topics, there are two dedicated to drawing errors. You may be able to prevent somebody making the same problems as yourself.

Thread: Those little screws for carbide inserts...
22/10/2019 16:44:54

I've just realised that my last thread was ambiguous, when I said "it broke in half", I was referring to the insert, not the screw. The tendency to disappear is the reason I have a supply of all the sizes I use in a box ready.

Thread: Pratt Burnerd 4 jaw Chuck jaw alignment
22/10/2019 14:42:36

If you do that, you are tensioning the jaws outwards, which defeats the whole object of tensioning them in the first place. They must be tensioned in the same direction as they are to be used.

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