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

You could try this previous thread:

https://www.model-engineer.co.uk/forums/postings.asp?th=163263&p=1

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:

https://www.youtube.com/watch?v=2kZPRzY8FSA

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:

https://www.youtube.com/watch?v=0bwRUf2wCyE

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:

https://www.t4i.com.au/R005

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 lathes.co.uk site says it was identical to a Student in all but centre height.

Could you confirm that the manual here:

http://manuals.chudov.com/Clausing/Colchester-Student-Lathe-Manual.pdf

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

16/01/2021 08:58:30
Posted by Bernard Wright on 16/01/2021 01:15:20:

Has anyone on here overcome this problem, I would really like to hear from you.

Could you please mention the make and model of lathe to which you are referring.

If you could post a link to the manual, then you will have a lot more chance of success.

Right now we are left to guess what lathe you have and what formula you have used.

Thread: Spur gear help.
15/01/2021 18:34:56

Just as an illustration, HPC Gears price for 10 DP is £23.42, £28.13 and £32.78 for 19t, 24t and 29t.

eBay prices for 20DP Myford gears are £10.50, £18.95 and £26.40 for 38t, 48t and 58t. The 58t seems to be less common.

A further option may be to use timing pulleys and a toothed belt if you can find a more economic source of supply than traditional spur gears.

Thread: Standards of Electrical Wiring
15/01/2021 09:13:07
Posted by Michael Gilligan on 14/01/2021 15:39:11:

...identify the boxes ...

The set up is similar to what I have seen in Ghana. The box is the electricity meter. This design seems to have a breaker integrated into the lower part of it. Generally, these are pre-pay meters. You go to the local agent with the meter number, pay your money and the meter credit is sent to the meter over the ether. The fat cable going in to the right is the electricity company's supply. The skinny cables are going to the property.

It is cheaper for the electricity company this way as they do not have to run their cable to each property: they give you a connected meter where they want to and you have to do the rest. Where it is situated also gives the best chance of it receiving the top-up credit signal rather than being up a narrow, dark alley at ground floor with three flats above it. It also minimises the risk of someone tapping into the supply cable before the meter.

Thread: Socket/thread sizes
14/01/2021 13:51:37
Posted by Martin Connelly on 13/01/2021 18:19:14:

...The 14SAE is the designation of the across the flats size that will have some tolerance so that it slips on and off nuts and bolts easily.

29/32" (23.02mm) is close to 23mm and a 1/2" Whitworth wrench width is slightly over this 23mm figure at 0.929±.003" (23.6mm) so a 23mm socket is also a 29/32" socket and a 1/2" Whitworth socket as all have a very similar across the flats value.

When I was buying tools as part of my job 19mm sockets were phased out and you bought a 3/4" socket instead since 3/4" is 19.05mm and the manufacturers saw no point in making and stocking 19mm and 19.05mm sockets.

There are a couple of points you might need to clarify to give your analysis some weight.

SAE is normally an abbreviation for 'Society of Automotive Engineers'. 'SAE socket', as a term, seems to be used as a contrast to 'metric socket'.

The difference between 19mm and 19.05mm is at least an order of magnitude less than the difference between 23mm and 23.6mm.

Using your logic for D1914, how do you explain D1929?

Thread: Schraeder valve threads
13/01/2021 17:53:41

For reference, including the term 'DIN 7756' in searches relating to tyre valve threads produces some good results.

Thread: peatol/taig parts
12/01/2021 17:30:23

A further option is to look at Axminster's Junior woodturning chuck. It is an ER20 chuck and can be bought with a 3/4-16 backplate.

The native Taig collets are very limited in the diameter they can hold, but do offer a very short projection from the spindle. ER20 will hold up to 13mm but does stick out a bit.

There are at least two other ER systems that fit a 3/4-16 spindle, the SCT from Chronos (but it looks to be discontinued) and the Beall (but this does not seem to be available in UK).

See:

https://www.quality-woodworking-tools.com/product/sct-collet-set-system-for-wood-lathe-3-4-x-16-tpi/

https://bealltool.com/products/turning/colletchuck.php

Thread: Boring bar size ?
12/01/2021 11:05:35

There are lots of things to consider. If you are going to pursue this as a business, and the job will repeat itself in the future, it is worth investing in the tooling to do it as fast and as easily as possible. That also extends to the method of workholding.

If it is a one-off, and you want to use the tooling more generally, than there are different considerations.

Inserted tool boring bars come in 16, 20, 25 and 32mm shanks as standard. The largest three of these four may not fit your toolpost, but you can make a dedicated holder (see https://www.youtube.com/watch?v=-55cbSUWSho).

If the things being bored are always 26mm minimum diameter, the most rigid off-the-shelf solution is a 25mm bar. But this is so tight to the bore that swarf management can become a challenge.

A 16mm bar 90mm deep is greater than 5:1 length to diameter. For a carb., you surely need a good surface finish for good gas flow and you have to take into consideration that it is an interrupted cut.

My suggestion would be a 20mm bar as it is just under 2 1/2 times more rigid than a 16mm one and it will still allow the cuttings a way out.

If the carbs. are die-cast aluminium, as Jason says, the sharp, polished inserts specifically for aluminium will help a lot in whatever bar you choose.

Thread: peatol/taig parts
10/01/2021 19:30:03
Posted by Nigel Graham 2 on 10/01/2021 18:54:01:

(UNF and UNC became common in the UK with American car manufacturers taking over ours, and by the ranges being for a time at least, the main system for NATO-standard military equipment.)

It is quite instructive to read the comments in this document:

http://practicalmaintenance.net/wp-content/uploads/Fundamentals-of-Threaded-Fasteners.pdf

starting page 13. It says that UNC and UNF were standardised in 1948 (before that, it was ANC and ANF) and by 1965 the British Standards Institution were requesting that they be considered second choice threads after ISO metric. So as a thread standard, it has had a surprisingly short life in this country at least.

10/01/2021 17:31:08

Searching for 'taig spindle nose' would have provided you with an answer. I believe the 3/4"-16 spindle nose is also used by the Sherline machines. You could search 'sherline spindle nose' to confirm.

It is also used by a few woodworking machines - inter alia the Clarke range by Machine Mart.

See also: http://www.peterchild.co.uk/chucks/threads.htm

Thread: Replacement Tips for Warco Indexable Lathe Tools
09/01/2021 17:06:33

The codes on the holders, strangely enough, are the codes for the holders.

In your search, you need phrase the query as 'insert for xxxxx tool'. The second letter of the holder code is generally the first letter of the insert code (but this is not true for the STDCR).

Five of the seven tools use standard inserts (of three different types - Cxxx, Sxxx and Wxxx). The threading and parting tools use a non-ISO insert but these are both currently shown as available from Warco.

I do not think you will not find this toolset among the Premier League ME suppliers, but if you have a scout around the other divisions (e.g. Chronos, RDG, Axminster, Chester, Armadeal) you might find that some of them are more forthcoming with info. than others.

Please see also this thread:

https://www.model-engineer.co.uk/forums/postings.asp?th=170078

but the RDG item mentioned therein seems to have disappeared from their site.

Thread: MIG Gas
07/01/2021 19:18:45

https://www.mig-welding.co.uk/welding-gas.htm

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