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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: Pratt Burnerd 4 jaw Chuck jaw alignment
21/10/2019 15:57:55

I'm pretty sure that nobody's checked the jaws of a four jaw independent before. Plenty of three jaw scroll chucks get tested. I would hold back from any grinding until other jaws have been tested properly.

When three jaw scroll chucks are ground it is important to preload the jaws first, which removes any backlash and tilts the jaws in their slots. Have the jaws in question been preloaded in the chuck body before testing, I think not.

Has a freshly ground three jaw chuck jaw been tested for squareness, I very much doubt it.

Edited By old mart on 21/10/2019 16:00:40

Thread: Two weeks wasted
20/10/2019 22:08:45

Buy her a bunch of flowers, then she will be keen to help you next time.angel

Thread: identify
20/10/2019 22:02:59

If it is old silver steel stock and good stuff, it will have "stubbs" on one end.

Degrease it and put it in some water overnight, silver steel is not rust resistant.

Mild steel is rarely ground, but silver steel is.

Edited By old mart on 20/10/2019 22:04:54

Thread: Pratt Burnerd 4 jaw Chuck jaw alignment
20/10/2019 21:57:16

I wonder if they were deliberately tapered to give a better fit when they are tight. You can test this theory, by turning a length of aluminium for a parallel smooth finish, and then clamping it nice and tight in the chuck. Do the jaws up slowly and as evenly as possible, and then look at the jaw marks on the bar to see how even they are. All chucks and jaws are subject to a little flexure when tightened.

I would prefer this to bellmouthing any day.

Thread: Self extracting drawbar for mill
20/10/2019 21:46:16

_igp2476.jpgI happened to notice messages and when I looked at them, one was asking how I went about making a captive self extracting drawbar for a mill. Now I have read it, the message has disappeared and the name of the sender has vanished. So I thought I had better explain how I went about this modification.

Not all vertical mills will be suitable to fit a captive drawbar to. I was lucky because there was space inside the spindle to fit a nut close to the lower end of the drawbar and also not foul the tooling.Some measuring will be necessary before any work is carried out. I cut the thread on the 7/16" en19T drawbar blank on the lathe, and put about 2 1/2" on either end. I made the bronze nut (in black) long enough to Loctite securely with a flange thick enough to not be in any danger of breaking off. At the top end, I used two half nuts for locking and a piece of threaded hexagon bar large enough to ensure that the upper locknut didn't foul the ring spanner that tightened and released the tooling. I was lucky to find a stub ring spanner with a handle of just 6" long, which is plenty. Due to the design of the mill, I had to put spanner flats on the bottom of the spindle, as there was no lock,or any way to hold it. With a minimum endfloat on the drawbar, it breaks the taper in 1/4 turn._igp2436.jpg

Thread: Two weeks wasted
20/10/2019 19:28:35

How about drilling a hole just a bit larger than the pins in a block of steel, or bar, putting that in a vise and when the job is heated up, quickly punch the pins out using a drift. An assistant would be a great help and a rehearsal before heating to get the procedure off pat.

20/10/2019 18:50:06

If you silver soldered the pins in, why can't you unsolder them? A solid carbide drill will work on even fully hardened silver steel, which it is unlikely to be anyway. Solid carbide should not be used in a hand drill as you will break it.

Thread: Problems with "The Home Shop Machinist" website?
20/10/2019 15:53:08

After being a member for several years, I managed to post my first photograph on the HSM. It now has a similar method to this forum.

Thread: DRO to vertical mill z axis
20/10/2019 14:54:16

If you aren't prepared to do some basic modifications to your mill you might as well forget the whole thing.

Thread: windoze 10
20/10/2019 14:49:18

There's yet another build coming to W10 sometime in November for the early adopters to get, but most pc's will not be forced to get it for some time.

Thread: Slideways oil
20/10/2019 14:43:24

Don't be put off by modern synthetic motor oil being thinner, the main reason why these oils contribute so much to engine life is their superior lubricating qualities precisely when the greatest wear is present, when the engine is cold.

Thread: angle plate
20/10/2019 14:36:58

The machining/grinding of the faces seemed to be left out of the video.

Thread: Slideways oil
20/10/2019 14:27:00

I have tried slideway oil and semi synthetic engine oil on the drill mill X axis, and it is always hard to move. The Y axis is good as gold. The Tom Senior rebuild has been lubricated exclusively with slideway oil, except for the leadscrews, which have spray chain grease and it is smooth in all its movements. The lathe uses semi synthetic motor oil for everything except the cross slide and compound leadscrews and is none the worse for it.

Thread: Lathe rigidity
20/10/2019 14:17:44

Great news. There are many useful things for us all to learn from a thread like this, especially that there is almost always a way to overcome seemingly impossible hurdles by lateral thinking.

Thread: Problems with "The Home Shop Machinist" website?
19/10/2019 20:02:42

There was concern that the old format was less secure than it should be.

Thread: angle plate
19/10/2019 19:30:05

Interesting project, I like watching these for tips on how to do different things.

Thread: Start of Tom Senior refurbishment.
19/10/2019 19:03:32

_igp2468.jpg_igp2467.jpg_igp2464.jpgI have cut some metal on the mill at last.

The slots in the bed are 1/2" while the drill mill slots are 5/8". I used the DM to rough out a replacement key for one of the 100mm Bison vises. It had a run across the rear jaw of 0.0015" which is understandable. The pictures show how I got the vise dead on with the X axis, the amount of actual milling amounted to a skim of about 0.002" climb milling on the rear of the key.






Edited By old mart on 19/10/2019 19:09:19

Thread: Problems with "The Home Shop Machinist" website?
19/10/2019 18:47:12

It is up and running with a new format, I had no problems adding a few comments just a few minutes ago.

Thread: Confession Time!
18/10/2019 17:17:33

They are technically challenging to some people. On one end there is a magnet, and they will not work if you hold then the wrong way round!dont know. I have a number of magnets on handles stuck to the wall behind the machines at the museum, the longest is 3 feet.

Thread: Bearing fit
18/10/2019 17:11:09

Loctite 601, 620 and 638 are part of their extensive range of BEARING FIT PRODUCTS.

Edited By old mart on 18/10/2019 17:11:41

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