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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: Mill DRO X/Y axis + and - on readout
21/03/2022 19:36:31

As Howard says, it makes no difference.

Depending on how you work, it can make life easier for you if it is a certain way.

Once you start using the DRO, you will rarely look at the dials again, so it does not need to increase in the way the dials increase. With a DRO, your dials only really need a settable zero mark. If you have to leave a particular setup, you can put the table at (0,0) and zero the dials. The dials will then save you time if there is a power cut.

If you use computer-generated drawings, or calculate co-ordinates using a spreadsheet or other program, it can be useful to have X- and Y- increase in the same way as normal Cartesian coordinate. (so I think that would be the opposite of your diagram - as the table comes towards you and moves to the left, both increase).

In the beginning, or if working very close to the 'zero' lines on your part, it can be helpful to mark these lines on the part, just so you do not confuse the sign (positive or negative.). You will see from your drawing if the feature should be above, below, left or right of the axis and the marked lines give you a visual reference to ensure this is so.

Thread: MT1 cutter arbours
21/03/2022 16:45:58
Posted by Trevor Drabble on 21/03/2022 10:15:58:

...ER32 collet system on a No 1 MT ....

Is ER32 on MT1 not just a little ambitious?

Another option is a soft blank arbor and make your own. RDG sell MT1 ones with an M6 thread in the back for a drawbar. Chronos sell tanged oned slightly cheaper should you want a different drawbar thread.

If you are tight on headroom on the machine, this is likely to be the shortest solution. If you go for the ER option, clearly, the bigger the ER-number, the longer the overhang.

Thread: Help with Excel
21/03/2022 14:45:24

Does anyone else find it slightly strange that the question was posed in imperial units and the diagram above is in metric? Clearly an engineer at work - perfectly correct but entirely unhelpful.

Anyway, if you want some magic words for Google, 'lautard radius turning' will help. Of particular note are:

http://www.swarfology.com/sphere1.pdf

https://rick.sparber.org/BTMNC.pdf

Edited By DC31k on 21/03/2022 14:46:21

Thread: Geometry question: What is the angle between two 45° chamfers, after the two connecting surfaces have been 'flattened'?
21/03/2022 07:24:29

Assuming that the chamfer is 45 degrees and the corner of the block is 90 degrees, you only need the chamfer distance to calculate this:

In either a side or end view of the part (does not matter because the chamfer is 45 and the corner is 90), you see the vertical height of the chamfer (top to bottom) as a true length (1). This is the chamfer distance.

In a plan view of the chamfer, you see the base length as a true length. It is the hypoteneuse of a 45 degree right triangle with side length = chamfer distance (2) .

Those two lengths allow you to calculate the true length of the intersection slope (the vertex of your unfolded pattern) (3).

The side or end view gives you the true length of the chamfer (the sloping bit) (4).

(3) and (4) allow you to calculate the half angle.

Using the same reasoning, you can write a general formula where the inputs are: chamfer angle, a characteristic chamfer distance (either vertical or horizontal) and corner angle.

A good place to start is an old technical drawing book, where you learn how to draw a view of something such that a particular feature is shown as its true length and its angle to a plane is a true angle.

Thread: Wavy Washer Supplier
19/03/2022 21:15:52

There is another type of washer that matches your description, commonly called a 'crinkle washer'. Its proportions are close to a standard flat washer of the same nominal size.

Searching on 'wave spring washer' brings up items with a very thin section (i.e. the ID and OD are much closer to each other than a standard flat washer). This type of washer is what you would normally see against the end of a bearing on a powertool or if you remove the end bell off a motor, hence it is quite likely that they are sized by OD. This would also explain the thin section - so it only presses against the outer race of the bearing and not onto the rubber seal.

Thread: Electrical outlet search
13/03/2022 10:09:12
Posted by Chuck Taper on 13/03/2022 09:21:04:

Why is it that all (aka - the overwhelming majority) of extension sockets have the cable exit on the right?

Your comment interested me enough to go looking, and you are correct.

Please see top of page 21 on CPC ctalogue: https://www.easyflip.co.uk/CPC_Catalogue/?page=845 The trouble is that this is a 2018 catalogue and CPC do not seem to stock this product any more.

I did not go looking for that particular one, but was trying to determine in principle if the modular, under-desk systems on the same catalogue page (and e.g. Toolstation 13987) could be configured for left hand drive. So that might be an avenue to pursue.

I have an old 2 x 3-way one of this style, by Formfittings of Rotherham and it is completely modular inside, meaning that you could rotate each individual socket 180 degrees (or 90 degrees if desired) to have the inlet on either side.

Thread: Any advance on the highlighted comment ?
13/03/2022 08:43:53

I wonder what the commenter sees wrong in the picture.

The two pieces of angle iron have been welded together into a C-section and bolted to the body of the grinder using the manufacturer-supplied threaded holes normally used for the side handle (you can see the head of the bolt).

He is drilling a hole in another part of the fabricated bracket in order to attach it to something or something to it. Having the grinder in place stops the wings of the C-channel flexing due to downwards pressure of the drill bit and also gives something to hold onto.

About the only thing wrong is that it is not clamped down.

Thread: Electrical outlet search
13/03/2022 08:38:42

Use some or all of the following terms in your search: 'metal clad', '4 gang', 'socket' possibly with the addition of 'industrial'.

It would help greatly if the photograph allowed us to read the text on the RCD in the centre.

A similar, modern, domestic version can be seen at Screwfix 3241F. This is eight gang, but it gives a manufacturer, BG, and Schneider, another manufacturer, pops up in the sidebar.

You will need to look through the catalogues of mainstream, name-brand electrical manufacturers for further inspiration.

Thread: Dividing head for Tom Senior Mill advice
11/03/2022 15:00:23
Posted by Andrew Johnston on 11/03/2022 14:18:18:
Posted by old mart on 11/03/2022 13:55:14:

...wanted 118 divisions, there was no way with the plates to get that...

Simple enough to make one, index 20 on a 59 hole plate.

I am not sure if your reply is tongue in cheek or meant to be serious, but if he had a 59 plate, he could produce the 118 from it directly. 118 = 59 x 2 and 59 is prime.

Thread: Drilling 38 x 1.5mm 316 polished stainless tube.
11/03/2022 10:19:08

Take a piece of the hardest wood you can find. Bore a 1 1/2" hole through it. Bore a hole through one side of it. Split that side of it with a saw and insert clamping bolt and nut. Bore another hole through the centreline of it to suit a 6mm ID steel tube that you secure with epoxy.Good quality HSS drill will do (Dormer A002 or equivalent).

Thread: 7/16 B S B Thread
08/03/2022 13:57:17

If you just need something with a 7/16" x 26 tpi male thread on it to plug a hole, seek out a suitable BSCY (or CEI) fastener. PTFE tape is your friend and the 5 degree thread angle difference helps it to seal better.

Thread: Milling cutter insert identification
05/03/2022 19:36:30
Posted by DiogenesII on 05/03/2022 19:12:10:

...I think some of the numbers might also refer to insert dimension, tip radius and ?maybe ?grade? or could be another attribute?

Thanks for the clarification. I must apologise for the vagueness of my post. The numbers to which I was referrring are the ones in the original post, that are printed on the holder/cutter body.

It would be good if someone could unearth a Collosus to crack the Sandvik Enigma.

05/03/2022 18:01:47
Posted by John Hall 7 on 03/03/2022 16:30:21:

It doesn’t seem as straight forward as identifying lathe tool inserts.

If the cutter uses a non-ISO insert, it will be proprietary to the manufacturer. Also, the technology may have moved on and the cutter and insert may be obsolete.

As the post above notes, the insert code appears to be as shown. Another possible source is Cromwell:

https://www.cromwell.co.uk/shop/cutting-tools/milling-inserts/r215-44-u-max%E2%93%A1-milling-inserts-grade-4030/f/78165

The R215.44 part seems to be the insert designation: the other parts of the code yout quote are probably specific to the cutter itself - number of inserts, shank diameter, length, etc.

Thread: Warco WM250V Screwcutting
04/03/2022 11:58:03
Posted by Andrew Douglas 1 on 04/03/2022 10:03:45:

So it looks like i need a 40 tooth and a 28 tooth as well as the 48 tooth.

Something else to take into consideration before selecitng a tooth count is the space available. A 28t gear will be approximately 50% of the diameter of the existing 48t one, so you might have to do some gymnastics with the indicator body in order for it to mesh with the leadscrew.

If the existing gear is 48t, a nearby one containing a factor of 5 would be 45 or 50 (45 good as it also contains 3; 50 good as it also contains 2). 49t is near 48t and contains the 7 you need, but its other factor is another 7 so it will be a one trick pony. If 42 will fit, that might do as it has 2, 3 and 7.

02/03/2022 10:56:25

Martin Cleeve's book, 'Screwcutting in the lathe' covers the thread dial indicators very well (Section 5 entitled 'problems and analysis of repeat pick up'. It is concise, correct and unbiased. It is prudent to read the US forum cited above with some wariness as many of the discussions there are motivated by a desire to denigrate the metric system

Think of the thread dial indicator as a counter - the fact that it is gear-shaped is not really relevant. It is no more sophisticated that what you see if you Google 'click counter'. Every 'tick' of the counter, instead of registering someone's entrance into an event, counts one leadscrew pitch (2mm in your case).

So, if the gear has 48 teeth, it will measure 96mm per rotation. The dial that is mounted on top of that gear will not have 48 graduations on it (corresponding to one graduation per tooth) as that would be confusing. Instead, it has 12 graduations (corresponding to 4 gear teeth). Thus, each graduation on your dial will measure 96/12 = 8mm.

For the thread dial indicator to be of any use to you, the distance it measures in one revolution has to equal an integer number of pitches of the thread you are cutting. If you are cutting 1.25mm pitch, 96/1.25, or (96x4)/5 is not an integer, so the dial is no use for that thread pitch.

I am assuming the threading chart on the lathe in the Youtube video above is the same as your own. In which case, your indicator will be useful for 0.2, 0.4, 0.8, 0.3, 0.6, 1.2, 0.5, 1.0, 2.0, 0.75, 1.5, 3.0mm pitches. That is 12 out of the 18 possible ones*. It will not be any use for 0.625, 1.25, 2.5, 0.875, 1.75, 3.5mm pitches.

Martin suggests a 40t gear above, and for the 1.25mm column, that will work. But more importantly than a specific number of teeth, what it is necessary to understand is that any gear that has teeth that are a multiple of 5 will do. Similarly, for the 1.75mm column, a gear that has teeth that are a multiple of 7 will be needed. The disadvantage of the 40t gear suggested is that it will not be useful for 0.3, 0.6, 1.2, 0.75, 1.5, 3.0mm pitches as those need a gear that divides by 3, which 40t does not. The other columns need a gear with an even number of teeth, which the 40t does have so it can be also used for those ones.

If you want one gear that will do all the missing threads that the standard 48t will not do, a 35t one would do both columns, but it also has the disadvantage that it will need two different dials for the top of it - one divided into 5 and the other divided into 7.

So, the thing to take away from this is that no single gear will work with all metric threads. What you can do is assess which threads you will be cutting most often and choose a gear that maximises efficiency for those threads.

* We could perhaps discuss how many of the 'possibles' are actually useful - I do not have many screws with 0.3, 0.6 or 1.2mm pitches.

Thread: Shaper tooling.
01/03/2022 15:07:46

If you think shaper literature is in short supply, you need to look harder or use Google a little better.

For examples of the toolholder, look on vintagemachinery.org for the catalogues from Armstrong and from Williams.

www.neme-s.org has a vast section of shaper literature as does the circuitousroot website.

Look on the internet archive for old textbooks that have been digitised.

Thread: Warco WM250V Screwcutting
01/03/2022 07:55:13

Following on as question 2, from Jason's initial one:

2) IF it is a metric leadscrew, what is its pitch?

3) How many teeth are on the gear of the thread dial indicator which meshes with the leadscrew?

Please view from 0:50 to 1:10 in this video:

https://www.youtube.com/watch?v=neMQS1TTibU

 

Edited By DC31k on 01/03/2022 08:20:51

Thread: I need to screw cut a 19 TPI thread.?
28/02/2022 07:29:26
Posted by Bazyle on 27/02/2022 18:22:59:

If you look at the changewheels provided for any non QCGB imperial lathe you always see a 38 tooth gear. ie 2x19

You need to qualify that remark by adding 'for the non-US market'. Their pipe threads use 11 1/2 TPI, so you are more likely to see a 23t or 46t gear.

The presence of a 23t/46t gear or 19t/38t in an unknown set of change gears can be a good indicator of the origin of the machine.

Thread: Tube Benders
22/02/2022 18:06:10

Buy from Screwfix, keep the receipt, measure the information you require, return for refund. Report findings here and earn the eternal gratitude of everyone.

The only small tube bender I could find that lists the radii is the Swagelok one and it is quite pricey.

If you want ot risk your cash, you can buy the 6mm, 8mm and 10mm one on Amazon for less than £11 (look for NBEADS, currently £8.99)

Thread: Meddings Pillar Drill chuck change
20/02/2022 20:14:36

This thread has some useful information:

https://www.model-engineer.co.uk/forums/postings.asp?th=165978&p=1

Dimensions for wedges, should you wish to make your own as attached (derived from measuring the ones supplied by Arc).

chuck wedges.jpg

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