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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: 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).


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

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:

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:

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:

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

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

Thread: Calculating Gears
07/01/2021 18:29:55

Consider two gears at a centre distance D. The two gears touch on their pitch circles, so for 1:1 ratio, each pitch circle has has a radius of D/2 or 1/2 * D. That means each gear has a pitch circle diameter of D.

The total (sum) of the pitch circle diameters is 2D and the gears share this 2D in proportion to their ratio (i.e. 1 * D each for 1:1 ratio).

Now, for 1:2 ratio, one pitch circle will have radius D/3 (or 1/3 * D) and the other 2D/3 (or 2/3 * D). The corresponding pitch circle diameters will be 2D/3 and 4D/3.

Again, the sum of the pitch circle diameters is 2D and the gears share this in proportion to their ratio (i.e. 1/3 * 2D for one and 2/3 * 2D for the other).

Let us try a 13:27 ratio. One gear will have a PCD of 13/40 * 2D and the other a PCD of 27/40 * 2D, the sum of the PCD's again being 2D.

So the general rule is to take twice the centre distance and pro-rata it according to the gear ratio.

This gives you the PCD of each gear that will fit in the space and achieve the ratio you want. These two numbers are inviolate.

You then choose a tooth count and calculate a DP/MOD for this count or you choose a DP/MOD and calculate the number of teeth.

For any given space and given ratio, you can use big gears with few teeth or small gears with lots of teeth.

Thread: Holding drills in ER collets
06/01/2021 19:32:16
Posted by old mart on 06/01/2021 15:13:35:

If you use very small drills, an er11 with a straight shank would be better...

That rather depends on how you define 'very small drills', since ER11 has a minimum gripping size of 1mm.

For true 'very small drills' I have not found much past a 0-3mm or 0-2mm Albrecht keyless, but they are very expensive. I would be happy to learn of a more economical solution for sub-0.040" drills.

Thread: straight shank adapter for MT2/MT3 drill bits
06/01/2021 08:39:26
Posted by JasonB on 06/01/2021 07:02:57:

...Modern SDS plus machine with a clutch and set to rotary only is a lot safer and the if you get one with vari speed even nicer to use. 1/2" chuck on SDS+ arbor will then hold your parallel shank adaptor.

There are some challenges with this idea.

The major dia. of the SDS shank is circa. 10mm, with its cross-sectional area reduced by grooves and slots. Its torque-transfer ability is therefore limited. Compare with the traditional way of holding oversize drills in a standard 1/2" capacity chuck - blacksmiths's drills (Silver and Deming). They have a full dia. 1/2" shank.

The adapters from SDS to 1/2" UNF for drill chucks are often made of low quality material, so when overloaded, they twist, making them very difficult to remove from the SDS chuck. This is especially a problem in rotary-only mode where the chucks's drive key bears on the same part of the adapter all the time, as there is no reciprocating action to create uniform destruction.

Your idea has merit if he wants to stand in his own house and drill a hole in his neighbour's one. There is a big issue with length. A Jacobs chuck on an SDS adapter sticks a long way out from the nose of the drilling machine. To that you want to add a straight shank to Morse adapter (minimum length slightly over the tapered length of the bit's shank) and into that you want to poke a relatively long Morse taper drill bit.

This one on eBay has suffered some bodgery but it has Morse taper (the ejection slot is shown in one of the pictures)

It seems Wolf and Kango had some connection so a search under that brand could help.

Also made by Black and Decker, when that was a good brand:

I have also seen an old DeWalt version of the same, in 110v.

05/01/2021 21:07:10

Posted by Pete Rimmer on 05/01/2021 20:49:16:

1. Buy a AEG/Wolf gutbuster which has a MT socket.

As an alternative to busting his gut, he might consider something that will help reduce his gut and keep him warm on those long winter workshop evenings:

Thread: Chester DB8
05/01/2021 20:51:59

Can I make a suggestion? The resources available when you type your query into Google outnumber those here on this little site, good though it is, by several orders of magnitude.

Thread: Vertex Dividing-Head - basic help please
02/01/2021 10:06:32

Would you be able to copy and paste the following into Google?

bs0 dividing head manual

There are many sets of instructions, the US-Grizzly ones are normally good. If reading is not your thing, there are some good videos on YouTube.

It would be prudent to do an independent check on the numbers given in the division tables. There have been posts here that the ones supplied with the rotary table dividing plates are incorrect.

Thread: Camlock spindle
02/01/2021 09:54:56

See post #39 here:

Thread: Between Centres Boring Bars
31/12/2020 10:49:04
Posted by John Pace on 31/12/2020 10:37:26:

This combination of a boring bar and boring head works well

That is very good. Is the connector providing the drive in lieu of a dog?

I have seen boring heads used horizontally and stationary in the tailstock for taper turning (saves offsetting and resetting the tailstock).

I think the same arrangement would work for between centres boring (i.e. it does not matter which end of the bar the boring head is). Is that correct?

31/12/2020 10:33:08

The one Jason suggested is very nice.

If you search 'boring bar micrometer' and look at images, some of the results will give you some ideas. Any that include 'Van Norman' are not what you are looking for - it is the ones that look like a standard micrometer with the fixed anvil replaced with a vee block.

A vee-block with a micrometer barrel strapped perpendicular to the vertices of the two vees would work. Replace vee block with an old centre-square body and add micrometer.

Grind a notch in the cutting bit diametrically opposite the securing screw. Use a second screw with a tapered end engaging in the notch to advance the bit. Very limited range of movement with this though.

Use a normal micrometer across bit and bar after doing an initial cut and measure. If diameter of cutting bit is so large that micrometer anvil falls into the hole, use a gauge block to span the hole. This does mean you have to shorten the butt end of the cutting bit shown in the photo.

See also:

OK, found it. Search for Moore & Wright 462.


Edited By DC31k on 31/12/2020 10:38:52

Thread: Tool identification help please..
30/12/2020 13:49:21

The eBay link by peak4 is for a double-ended insert. This will not fit.

GTN inserts will not fit.

MGMN inserts will not fit as they are again double-ended.

Have a look at:

I think the parting tool is the same. The photo is a bit small. Check the other shank sizes in the same range to see if anything more visible is shown.

If you can establish identity, the insert code is given on that page - it is not SCMT or WCMT. The two JCL15 references with I and E are, I guess, the internal and external screwcutting inserts. By a process of elimination, that leaves CK3.

Please ask someone else to critique this analysis before committing your cash.

See also:

Edited By DC31k on 30/12/2020 13:51:29

Thread: CAM software for CNC Lathes - With C axis and constrained live tool
30/12/2020 09:25:06

Can I mention a couple of ideas on the periphery of your request?

Have a look on the Dolphin site, particularly among the documentation for the milling
module. That describes a way to 'unwrap' the A-axis so the machine treats it as a linear
axis. With a bit of thinking and post-post-processing, that could work for a C-axis. I
think there is a program called G-code unwrapper that does the same thing.

Have a look on the madmodder site for some posts by Andrew Mawson. He has a Beaver CNC
lathe with C-axis capability. He wanted to mill a hexagon onto the end of round stock with
a live tool. His solution might give you some things to think about.

Have a look at the K-Flop controller. That is very configurable.

Have a good think about what you want to use the C-axis for. For instance, if you are
making a cam, the cut surface is just a series of (X, C) coordinate pairs with a bit of tool
positioning before and after.

It is not too difficult to use (spit!) Excel to generate the meat of the geometry and then
hand write the intro. and outro. Much easier in something like python, with the benefit
that python interfaces easily to dxf so some automation of input geometry and sanity
checking of output is possible (see also a program called CNC simulator)

If you want to mill a polygon on the end of stock, you just have to work out the equations
for one side, do a turn at the vertex and repeat for the other n-1 sides.

Hole patterns in the face is a simple index, peck and retract and repeat.

So my suggestion is to hand code the C-axis stuff. Once you reach the limits of this, then
go looking for a commercial solution.

I am not sure why the spindle zeroing before starting C-axis operations is causing you
distress. Say you are holding square stock and you want to notch it at the midpoint of
each side after turning the end of it round. Once the turning is finished, you switch to
C-mode, jog the axis so that the stock is in a known position (use a square off the lathe
bed, for example) and then zero that axis in the controller. Then load and run your C-axis
code. If you watch the Edge Precision YouTube videos, that is what he seems to do on a
multi-thousand dollar Mazak machine.

If you think about what you are asking, the machine would need to keep track of the
spindle position from the moment it is switched on and you would need to load the stock
into the chuck in a specific orientation. You do not set the DRO on your mill to 2mm
and then push the stock around on the table until the edge finder jumps. You clamp it down
anywhere, touch off and then type 2mm into the DRO.

On the spindle control, the only servo with which I am familiar is the Mitsubishi one. On
this, the motor has three modes of operation: position, speed and torque. For position
control, you feed it step and direction. For speed control, it needs a 0-10v analogue
signal. To switch between modes, you change the logic level of a couple of input pins on
the servo brainbox. This is easy to do in something like Mach3 and is an exact copy of
what it does for flood or mist coolant on/off.

So you need to be looking at the servo controller documents to see how it wants to be
mode-switched and then build something that will do that (possibly with a break out board
if it is something strange). The 270kHz for maximum spindle speed is likely to be a big
stumbling block. Mach3 will not do a lot more than 10% of this. As someone says above,
LinuxCNC is 110kHz. So look very hard to see if there is a way of controlling the spindle
speed by analogue methods. If not, you might have to build a dedicated circuit.

Thread: Milling cutter
26/12/2020 21:11:12
Posted by Chris Evans 6 on 26/12/2020 20:35:01:

I may have some TPUN inserts that would possibly fit, they are a turning tip but a quick touch on a diamond wheel and they work well for milling. I will look tomorrow and if I have any I will let you know and post for the cost of posting.

When you post them to him, how will you send him the hole in the middle of the insert, that he needs for securing it? The second 'T' in his TCMT is quite important...

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