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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: I need a Collet nut
26/01/2021 20:40:08
Posted by JasonB on 26/01/2021 19:59:39:

I doubt a German tool would have Whitworth threads, more likely Metric are you sure it's not M18 x 1.5

Page 8.

If I read it correctly, it is a strange one at M18.5 x 1.5. And you are correct. There is no collet in the world to fit that opening.

26/01/2021 17:35:52
Posted by Oldiron on 26/01/2021 16:33:18:

Would it be a major job to make your own nut. I presume you have the spindle so will have thread size & cone angle. Most other dimensions can be a compromise.

It might be good to look at the item about which he is talking - see Jason's link. It spins at 12,000 rpm.

For an item engineered to work in proper balance at that high speed, the £60 quoted above is a bargain.

Thread: Bridgeport power feed
26/01/2021 16:19:23

Yellow building site transformer.

Thread: Squareness gauge
26/01/2021 16:17:31
Posted by old mart on 26/01/2021 15:44:10: could be checked at the desired top and bottom heights and adjusted to be true at those points.

You are correct, providing that squareness is needed to be checked in only one place. On YT, both OxTools and Stefan Gotteswinter have shown versions that do this.

On the other hand, if you need to sweep from top to bottom checking squareness, then the height gauge may not be good enough.

Thread: How big Are Your Chips
26/01/2021 09:46:52

Posted by Ramon Wilson on 26/01/2021 08:32:16:

Nice one - but I'll bet if that came off a planer the work piece was correctly clamped down

I wonder if you can infer anything of the chip's origin from the hand of its spiral.

I am trying to visualise it. I think conventional turning on a lathe would make a right hand spiral.

What of shapers, planers and vertical lathes?

Thread: Motor reverse switch 3 phase
23/01/2021 10:43:50

If it has a truth table, you are halfway there. Use your continuity meter to translate into layman's terms what the truth table is telling you.

Martin has already told you all there is to know on the subject: to reverse, swap any two of the three phases.

In the off position, the three incoming connections, call them U, V, W, will not connect to anything at all.

In the forward position, U, V, W will make to A, B, C respectively.

In the reverse position, U, V, W will make to B, A, C (or similar).

It is very important for your own safety and peace of mind that you understand what is going on rather than just follow a recipe that says 'connect this to that'.

23/01/2021 09:26:31
Posted by Martin Connelly on 23/01/2021 09:10:54:

There are probably lots of wiring diagrams for dedicated switches but since the dedicated switches will be likely be just 2 or 3 positions (forward/reverse or forward/off/reverse) they will not help.

If we take the concept of a three phase reverse switch and the number '12', a good possibility is a fwd/off/rev/off cyclic mode of operation*. That would correspond to a 4 position switch in your terminology above so the diagrams for a 3-position one might at least give a starting point.

In the absence of a proper wiring diagram, use a continuity meter and make up a truth table for all terminals and all switch positions. Publish it here for review and we can tell you how to connect it.

Why not publish a link to the switch you have bought? Or if the source of your switch breaches the rules here, find an identical one from a 'clean' seller and point us in its direction.

* That is how the classic Santon ones work, even if the legend plate only has three marked positions.

Thread: BSF vs BSB threads
22/01/2021 22:00:01
Posted by duncan webster on 22/01/2021 21:29:20:

Even tho' the pitch is constant the helix angle will change with diameter, so do you really get away with just one set of thread rollers?

That is a very good question.

I went looking here:

and found

If you look at the second page of the document, for BSP threads, the closest to a constant pitch easily to hand, the rolls only cover a limited range, so I think your observation on helix angle is well made.

Special mention of the technical info. page above as there is a lot of stuff there on Coventry die heads, particularly the sharpening thereof.

Thread: Running a 3phase at home
22/01/2021 19:17:28

Best tip I can give you is to write down two things: how much money you wish to spend and how much time you wish to spend.

If the first of these is a high number and the second a low number, the solution that works for you will be different to that if the first is low and the second is high.

Thread: Clarke collet chuck
21/01/2021 20:29:02

Have a look at post No. 16 here:

There, they are called Q24-16.

Life is very circular. That site also references this site:

where the drawing above first appeared.

Thread: Princess Royal Oval buffers 3 1/2 H P Jackson
19/01/2021 12:55:40

I do not know if it is any help, but there seem to be some good photos of the class here:


Perhaps send a suitable donation to these people and they will pootle off into their shed with a tape measure for you:

Edited By DC31k on 19/01/2021 12:57:47

Thread: Deckel fp1 feed gears
19/01/2021 09:05:22

You could try this previous thread:

Thread: Chuck fitment to dividing head
18/01/2021 18:39:47

If it does turn out to be as Michael suggests and if you can live with the increased stick out, make an adapter that is 1 1/2" - 8 Whit. form internally and 1 1/2" - 8 UN form externally. The chucks will then screw on to it and project a bit further from the face of the head.

Does the dividing head have an internal taper? It is possible to buy 2MT to Myford spindle nose thread adapters, so you could make something that does the same job (but nothing can poke out the back of the chuck).

Thread: Myford ML7 4 way tool holder
18/01/2021 15:08:09

Would it be worth measuring the overall thickness of your compound slide, including base, and asking someone else to do the same to confirm they are the same?

Maybe do the same for the 4-way toolpost, but measuring from underside to bottom of tool slot.

Even measure from the ways to the top of the cross-slide and compare.

Finally, check spindle and tailstock centre height above ways.

Thread: Lathe Tool Height
18/01/2021 12:52:12

It is very good advice above to keep the shim with the tool so you only have to set it up once.

I think there used to be a set of shims you could buy precisely for this purpose. They would look like a square-ended,very fat set of feeler gauges. I have seen pictures of them used in a four way indexing toolpost, with the unused leaves rotated 90 degrees into one of the unused tool positions. I cannot find a picture of them but found a similar concept in wood:

Anyone recall them or remember what they were called?

Thread: Advice on best approach to milling recess in end bar
18/01/2021 09:37:23

The difficulty with the part is the solid centre. If it were possible to remove it, machining becomes easy. If it is crucial for the part's function, consider removing it, milling the three teeth and then gluing in a disc to replace it. With a hollow centre, the part is just like a dog clutch, see:

Thread: Vertex (V4?) Rotary Table
17/01/2021 16:24:39
Posted by martyn nutland on 17/01/2021 14:58:55:

Apart from the main 360° scale on the table I have 120 divisions behind the hand wheel (two hours?) and then six divisions on the inner scale (tenths of one minute?).

There is a manual describing the parts here:

As that is an Australian version, the table might go in the opposite direction when you rotate the handle.

As others have said, it has a 90:1 worm ratio. Hence, one turn of the 120-division wheel moves it 4 degrees.

At this point, your description and the manual linked to diverge as it claims the micro collar resolves to 1 minute, which implies 240 divisions.

In any case, if your inner scale has six divisions, it will not be tenths of anything, but sixths, more specifically sixths of whatever one division of the outer scale represents.

Mr not done it yet's post contains some serious typos, so should be read with caution. To correct it, substitute 'diameter' for the first mention of 'circumference' and '12 seconds' for '12 minutes'.

Thread: Metric thread cutting on a Colchester
16/01/2021 14:57:03
Posted by Ian Parkin on 16/01/2021 12:11:21:

what does all that mean in practice?

Let me preface this by saying I do not have either a Student or Master lathe. Everything I have written is as a result of reading the manual linked above. If you also read it, you will see where the terms come from.

Let us go back to your original post. You say you have a way to cut 3.5mm pitch using 35t, 21t, DA, and 1.5mm gearbox setting. So if you want 1.75mm, that is half (or double) 3.5mm. The easiest thing to do is to change the arrangement of the levers that give you the two letter combination. This is exactly the same as changing the 1.5mm gearbox setting to 0.75mm (or possibly 3mm).

From the manual above, there are two levers, one with A, B and the other with C, D. That gives four possible arrangements of levers. On page 17 of the manual above, it gives a value to be used with each combination. The values are 1, 2, 4 and 8. From page 17, DA corresponds to a value of 2 so for 1.75mm pitch, you would need to try either 1 (AC) or 4 (BC).

The reason I am hesitant to commit myself is that I always get confused over the halving or doubling, especially when metric (pitch) rather than threads per measurement unit are involved. It is a case of try both options: one will be correct.

As to my post above, it is just the results from using the formula on page 17. X is the gearbox position, shown in the manual as (16, 18, 19, 20, 22, 24, 26, 28, 30). To find the 'best' ratio, you have to try all nine possibilities.

The formula tells you to convert your desired metric pitch to an equivalent teeth per inch. If you do that, you end up with a set of nine driver/driven ratios all with a multiple of 127 in their denominator. And you cannot have that because the manual also tells you that the biggest driven gear can only have 64t (and the biggest driver 60t).

So you then find a handy online continued fractions calculator and ask it to give you the closest fraction it can to the exact one, with a maximum denominator of 64. You then back-calculate the teeth per inch each of these nine approximate fractions give and sort from best to worst.

The best, [18, 32, 43] above, gets you 1.7502mm pitch (14.5125 tpi). The worst, [24, 63, 64] gets you 1.736mm pitch (14.6286 tpi).

Edited By DC31k on 16/01/2021 15:02:27

16/01/2021 12:00:13

The following is worked out using the formula given in the Student manual linked above. It may or may not apply to your machine.

The manual notes the following limitations on the gear tooth sizes: maximum driver 60t, maximum driven 64t.

For 1.75mm pitch, use AD (Y=2) and for 3.5mm use AC (Y=1)

Best to worst, written as [X, driver, driven]

[18, 32, 43] [30, 31, 25] [20, 43, 52] [26, 43, 40] [16, 41, 62] [28, 44, 38] [19, 22, 28] [22, 30, 33] [24, 63, 64]

16/01/2021 10:21:28

It is difficult to find a manual online for the Master. The site says it was identical to a Student in all but centre height.

Could you confirm that the manual here:

has the same gearbox layout and formula (page 17) as your own.

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