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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: Mystery Inspection Item
16/08/2020 19:17:02
Posted by gerry madden on 16/08/2020 11:12:21:

Hi Martin, may I ask who was running this auction?


Perhaps you might look at this auction:

Pay particular attention to the position, colour and design of the rule in the picture and the drainpipe on LHS. You may have seen them before...

16/08/2020 07:51:20
Posted by David George 1 on 15/08/2020 23:07:59:

Hi Martin they look like micromiter setting pieces.

Used for very small woodworking joints then?

The pieces differ in length by 120mm. I would be interested to see a micrometer that has this range of motion as the usual ones operate over 25mm or 1".

The head off one would be good for a lathe carriage stop or a milling machine length or depth stop.

Thread: Motorising the feed screw
16/08/2020 07:44:12
Posted by Alan Charleston on 16/08/2020 07:29:37:

I'd like to do the same. I have a couple of stepper motors but I can't figure out how to control their speeds using a potentiometer.

Using a stepper motor for this is rather overkill, especially as you say your Arduino skills are developing.

The whole point of a stepper is that it gives you positional/angular control. All you need is variable speed. This is more simply achieved using a DC motor (coupled to a reduction gearbox as necessary) and the ubiquitous PWM speed controller.

If you really want to go Arduino, take it in small bites. Put a potentiometer on the analogue inputs to the chip and work out how to send from 0 to 255 to your screen.

Then investigate how to drive a stepper motor at a fixed speed from the Arduino (there are pre-written libraries that do this - all you have to do is give them two numbers: direction and speed).

Then glue the first and second together.

Thread: Height Gauge
15/08/2020 18:54:05
Posted by Bandersnatch on 15/08/2020 18:38:51:

I managed to ferret this out for a UK source. The same company has them on eBay UK too (lower price on eBay for some reason)

Where it says:-

Range: 0-150mm

Reading: 0.02mm

might be slightly at odds with his requirement for an imperial one.

Is the eBay one imperial?

15/08/2020 15:07:46


Thread: Mystery Inspection Item
15/08/2020 13:31:30

Somebody else has one anyway

(seller has quite a few for sale. The numbers appear to be half their length).

Thread: power feed for miller
15/08/2020 13:17:17

If it is AC, it does not matter which you connect to live or neutral, but US wiring uses black for live.


As John says, you need a transformer. A standard yellow building site one is cheap.

Thread: Pinnacle bench drill chuck key
15/08/2020 13:13:48

Have a look at:



to see if they help.

Also, if the keys you have either mesh too tightly or too loosely, you can press the sleeve on or off to adjust. See:

Thread: Rotary Table Choice 36:1 o 90:1
12/08/2020 14:25:42
Posted by Howard Lewis on 12/08/2020 08:26:50:

90:1 gives better resolution = greater accuracy

I have just picked a rusty M6 bolt from my stock and welded a 70mm dia. piece of steel to the end of it.

The piece of steel happens to have 200 equally-spaced marks around its perimeter.

This means it has a resolution of 0.005mm so it must be more accurate than my Mitutoyo micrometer as this only has a resolution of 0.01mm...

11/08/2020 19:49:41

If (and I repeat, if) you go down the route of adding dividing plates to it, you will almost surely have to calculate all the plate and hole numbers for the 36:1 ratio table.

In contrast, you can find many published/printed information tables for a 90:1 ratio device (though some have errors).

The maths is not hard but if it is not your desire to do the calculations, that might be a small point against the 36:1 device.

Thread: Bantam thread cutting set-up?
09/08/2020 19:03:59
Posted by Rob Thomas 4 on 09/08/2020 17:50:54:

My question is when setting up for screw cutting do the driver and driven cogs run on different cogs of the compound idler(120T/127T).

I am assuming it is a native imperial machine (i.e. 4tpi leadscrew).

When screwcutting imperial threads, you use only one of the 120/127 pair. It is used only as an idler gear so does not change the ratio. Thus either one of the two is OK to use.

When screwcutting metric threads, you need to use both gears as a compound gear. This provides the necessary imperial to metric conversion factor.

Thread: Facing bar ends parallel on the lathe.
08/08/2020 09:13:50
Posted by Ady1 on 08/08/2020 06:49:19:

I believe that most lathes are set up a bit convex or concave to start with

Have a look on the Stub Mandrel site for Schlessinger's work and then you will know rather than merely believe.

Thread: Colchester chipmaster variant
04/08/2020 08:03:24

If you call the item by its correct name, a variator, you will have more success in your online searches.

There is a madmodder thread on disassembly and fettling, as well as one on Practical Machinist.

Two commercial sources, should you need them, are Allspeeds and Nottingham Electrical Transmissions.

As well as the factory manuals which Stuart will no doubt avail you of, download the Harrison 10AA manual from

as this has a section on variator maintenance.

Thread: Colchester master gear 56T
28/07/2020 19:54:55

The gear you require surely has to mesh with at least one other gear.

You can find the details of the one you want from the one you have.

The width will be the same as the meshing gear.

If you tell us the number of teeth and outside diameter of the meshing gear, we can calculate the gear specification and tell you the measurements for the one you need as well as the cutter that will produce it.

Thread: Milling Insert Clarification
25/07/2020 18:41:18

Thread: CNC Gear Hobber
21/07/2020 14:35:57

21/07/2020 08:38:06

Put 'stevenson gear hobber' into Google.

Read and digest everything you find (including the back issues of MEW).

Then you will be in a better position to understand the state of the art and crucially the boundaries/limitations of the method. It is this understanding, more than anything else, that will determine the success or failure of your venture.

Look at the electronic leadscrew thread here and on YT. Same basic principle of electronic gears rather than mechanical gears.

Software and encoders are 'industrial Lego' and are easily replaced.

Thread: Wohlhaupter UPA4 Boring and Facing Head Operation
13/07/2020 20:13:53
Posted by John Hinkley on 13/07/2020 19:24:04:

I can't see that there will be massive differences between UPA-3 and -4 models

There is.

That is why the manufacturer produces two manuals only. The first covers UPA1, 2 & 3. The second covers 4, 5, 6 & 7.

11/07/2020 21:23:06

Maybe less brief:

Possibility of help:

Patent images:

11/07/2020 13:29:18

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