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Member postings for DC31k

Here is a list of all the postings DC31k has made in our forums. Click on a thread name to jump to the thread.

Thread: Hardened and chromed steel rod
19/04/2020 18:53:44

Have you tried hydraulic ram suppliers and rebuilders? This material is their daily bread.

Alternatively, what about gas struts for toolboxes, hatchback car doors, etc.?

Once you get under the chrome, the rod is easy to machine. You could grind it off gently if you cannot turn it off.

Thread: Manual control of CNC
19/04/2020 14:04:02

As others have said, the term you need is 'manual pulse generator'. The software you use to control the machine will determine if and how many MPGs you can use.

They can be used by Mach 3. I believe most of the ones you can buy are 100ppr and you can set a distance in the software for how far one pulse moves the axis, so you do not need to spin the MPG like a turbine if you need to move a long way.

You can buy or build a pendant control with E-stop, MPG, axis selection switches and jog distance switches on it.

Lots of information in the Mach 3 archives.

Thread: CNC Feasablity for small project?
18/04/2020 20:16:55

Can you size the radius of the groove and the angle of the slope to suit a common horizontal mill cutter?

Run your 20mm stock through the horizontal (two passes) and then transfer to CNC.

Thread: Burnerd Multisize collets vs Crawford Multibore collets
18/04/2020 20:09:59
Posted by Adam Harris on 18/04/2020 19:49:09:

...I was viewing the Multisize EC collets as a type of 6 jaw chuck (and MC as a type of 8 jaw chuck) but am disappointed to read that not recommended for holding short ends of bar which I though might be a particularly useful extra benefit over a 3 jaw this so and if so why?

If you have been reading up on them, you will know how the collet is constructed (i.e. six 'fingers', spring loaded) and that each collet has a relatively large grip range.

If you try to hold something shorter than, let us say, 2/3 of the finger length, the fingers are likely to try to cant in the tapered bore of the closer, pivoting about the back end of the stock. It is much the same issue as with ER collets and short items.

If you want to grip short stuff, you need an 'enveloping' type like a Morse taper, 5C or W-type, with its correspondingly very limited grip range.

Thread: 3mm pitch chain
17/04/2020 16:58:36
Posted by John Haine on 17/04/2020 14:27:34:

If you search online there's a website somewhere that says how to make your own cycle sprockets, iirc mainly by hand.

Is it this one?

If you are at all CAD-minded, download a dxf of a 6mm pitch sprocket of the correct number of teeth and scale by 50%. Add a few centres for the rollers, print out, stick to blank, drill, saw file, done.

17/04/2020 13:03:56

I do not think 3mm pitch chain is made under any international standard.

Somewhat confusingly, 03B chain in an ISO standard is 5mm pitch.

These people:

say they can supply.

The only reference I found for 3mm pitch sprockets was for Chinese-made mini-motorbikes (pit bikes).

As Roy says, maybe make your own. Start with a decagon of 3mm side and go from there.

Thread: Metric taps and dies - and pitches
16/04/2020 13:47:15
Posted by derek hall 1 on 16/04/2020 11:56:12:

I am sure there is a table showing the preferred/standard metric tap sizes and pitch for Model Engineers somewhere

Tubal Cain, "The Model Engineer's Handbook" Third edition. Page 47.

If you search online long enough, you will doubtless find a pdf copy.

Thread: Source for 1.4310/301 stainless spring steel strip
15/04/2020 06:32:33

If you have to buy the coil, you could make a straightening device similar to that used for wire. It is just pairs of bearings in rows. The other classic way of straightening wire is to put considerable tension on it. Maybe this would also work with strip.

Thread: Percival Marshall Speaks - Model Engineering Video
14/04/2020 16:25:44
Posted by Dennis WA on 14/04/2020 14:14:26:

The article is : "No limits: George Schlesinger" by Alan Bester.

MEW No 246. Autumn 2016

Thankyou. I know of this one but would have to buy a back issue to see it. I would like to locate a copy of the original pdf that was on the website. I mentioned it as well more as an example of the non-permanence of internet stuff.

14/04/2020 11:16:17
Posted by Michael Gilligan on 14/04/2020 09:28:39:
.. which seems a little odd; because clicking ‘parent directory’ then takes you to the home page [where there appears to be no link available]

That is my point. You know where to look so you can confirm it is still there. But if you did not know, how would you go about finding it?

It is only through someone's chance remembering of your old, old posting that it has been found.

Try and find your original post as if you did not know it was there. In theory 'percival marshall' should eventually find it but you have to sift a lot of material.

Try and go at finding the audio file cold using the best Google-fu you have. If the file just sits on a server with no other page linking to it, it is almost impossible to find.

I suspect it used to be pointed to from the neme-s homepage, which is how you found it a long time ago, but that the neme-s page has been edited and the link removed.

14/04/2020 09:00:52

Would it be possible to download and archive the sound clip on the Stub Mandrel website?

Until you made the video, the only place it could be found was on the website, and it is not currently to linked on that site. Try and find it yourself on neme-s.

It was only the excellent tip off in the other thread, pointing to its original mention in a further old thread that lead to it seeing the light of day.

Things on the net are not permanent, so the more places they are, the more likely they are to survive. There is another thread on here mentioning an article on Schlesinger limits by a South African guy which can no longer be found (I believe it was somewhat turned into an article for MEW). If this were also located again, it would be good to host it.

Thread: Myford 254 thread dial indicator
14/04/2020 08:51:12


If you have a 3D printer, the world is your lobster as your namesake once said.

There is a free program called GearDXF which will give you a 2D dxf file of any gear for which you give it the correct parameters. You can then extrude this for your 3D print. So you can give it the correct module for 3mm pitch and the correct pressure angle (15 degrees). Have a think how you will secure it to its shaft and incorporate a keyway if required.

The 35t will do both threads but needs different graduations on the dial. For 1.25mm pitch , you will need 5 graduations, that will be spaced every seven teeth of the gear. For 1.75mm pitch, you will need seven graduations, spaced every five teeth of the gear. That is why the dial faceplate needs to be removable and reversible (and positively located on the spindle). Again, this could very easily be 3D printed.

Thread: Pultra 15/90 collet drawbar
13/04/2020 15:18:12

Posted by simon watts on 13/04/2020 09:22:21:

...RCM adaptor probably an easier option than the tap.....very expensive postage though...

If you can make one for less than the RCM one costs posted to you, I will take 5 please.

You have been provided with information that will get you a working W20 drawbar for less than £50. What were you expecting to pay for this unusual item? Good job you didn't ring Floyd Automation and ask of the Schaublin one.

Thread: Myford 254 thread dial indicator
13/04/2020 15:05:23


The term you are seeking is 'circular pitch'. The leadscrew has a pitch of 3mm. Acting as a rack, it has a pitch of 3mm. The proper gear to mesh with it has a pitch of 3mm, albeit that pitch is wrapped around a circle, hence circular pitch.

In metric gear terminolgy, a 1MOD gear has a circular pitch of pi (3.14mm). For 3mm circular pitch, you would need a cutter of 0.95MOD which is very non-standard. Hence, I would use an M1 cutter.

There is another issue to mention, but about which you need not concern yourself for a TDI gear, and that is pressure angle, the gear equivalent of the thread angle of your leadscrew. Your leadscrew, if metric, will have a trapezoidal thread of 30 degree angle. The correct gear cutter should have a pressure angle of 15 degrees. Standard metric cutters are 20 degrees, but it does not matter in this case.

Each cutter in the set of 8 has a range of teeth which it is good to cut. So you pick the cutter to suit the number of teeth in the gear you are cutting. I hesitate to mention a number for you as a lot of modern Chinese-sourced cutters have the numbers reversed to the traditional system (1 in traditional is 8 in Chinese).

When cutting the gears, I would be tempted to cut them both on the same size blank (i.e. a blank sized for twenty and a half teeth) then you do not need to alter centre distance when swapping gears. Also cut them relatively thin and you do not need to worry about skew angle.

If there is enough space for it to fit, consider cutting a single 35t gear and having interchangeable graduations on the dial (sheet metal held on with magnet, 5 graduations one side, 7 on the other). It is a lot easier to flip this over than to fiddle about behind the apron changing gears. The biggest challenge with this is finding the space for a relatively big gear.

Thread: Help required with Colchester lathe
12/04/2020 20:17:04

When you say it fails to disengage, what do you mean? Does it push the bed stop along the bed? The bed stop needs a good yank on the Allen key to secure it. Dismantle and fettle the stop so it works very well.

I think your concern about the bar is a chimera. The springing just gives the latch an easier time when engaging and reduces wear on it.

If you look at a post above this, on 14/04/2015 22:05:02 by Breva you see low down on the left spring 201-190-0 and adj. screw 201-164-0 (one each side of the worm). These are where the adjustment is made. The worm slides on its shaft (I think it has a pin in it that goes through the slot in its shaft). The spring pressure each side is what determines how soon the worm will move and disengage the feed.

You could try reducing the spring pressure but it is a ball-ache to adjust. I think it may be made easier if you temporarily omit the half nut interlock as this then allows the casting to swing down. Measure how far in the screws are before you start so you can return to 'before' if necessary.

I will think of a way to measure how much force it takes to trip it on mine and let you know.

Thread: Delapena Logo on the net?
12/04/2020 15:36:36

This one any good?

Put delapena into Google and then look at images.

Maybe something there will be what you want.

Thread: Dismantling a Pratt Burnerd Grip Tru Chuck
11/04/2020 17:29:23

The thread to which Mr old mart refers is here:

and it is Mr ega who kindly posted the diagrams.

11/04/2020 14:10:37

What size is the broken off bit? Is it hardened (check the piece that did come out)? How deep inside is the broken bit?

Drill it with a left hand drill. If that fails to shift it, tap it left hand thread. Screwing in the tap will screw out the broken bit. Left hand drills and taps from Tracey Tools. If it is hard, carbide mill and drive in a Torx bit.

Thread: Pultra 15/90 collet drawbar
10/04/2020 21:17:20

See also this thread:-

where Floyd Automatic is mentioned. On page 38 of their brochure at:

you can buy a part-drawtube, internally-threaded W20 and external M19 x 0.75.

10/04/2020 10:13:11

W20 taps are available from China on eBay (about £55).

rcm-machines sell a W20 internally-threaded adaptor (I think it is M12 the other end). That might be a good starting point.

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