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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: Push broaches for square holes
08/02/2021 07:08:19

You are concerned that £100 is an excessive price. Examine carefully the item you would receive for that money and ask yourself if you could make something of equal utility for the same price. DuMont's site in the US is a good place to start to gen up on broach technology.

In addition, it may simplify your work, open up tooling options and ease the path of any tooling you do use if you can critically examine the 'deepish' nature of the holes. Consider what depth the actual square portion needs to be and any part that does not need to be square see if it could perhaps be made circular of a diameter equal to the across-corners measurement of the square.

Thread: 8mm shank parting tool blades, where to buy?
04/02/2021 21:11:33
Posted by Stuart Cox 3 on 04/02/2021 20:21:19:
Thanks, I did take a look at the RDG tools listing before but they don't seem to list one at 8mm.

Sorry, clarity fell away in the search for brevity. I was going off the ArcEuro description that says it is 8.3mm high. There are a lot of 5/16" x 1/16" blades listed, but they might not be tall enough and possibly too thick. The RDG one is the correct 1.5mm width but 10mm high, and could be reduced on its underside by 1.7mm.

04/02/2021 20:10:00

Are we allowed to mention bona fide UK-based eBay sellers here?

RDG Tools list something suitable, as does MaxT Engineering Supplies.

The item numbers, if they survive the censor, are 351498912133 and 372619224936.

Thread: spindle thread
04/02/2021 17:52:53
Posted by colin hawes on 04/02/2021 16:47:44:

DC31k is correct; the thread will be 1 3/8 x 8

If you have understood my post as saying this, then I am sorry that I did not write more clearly.

A simple OD measurement of the register would give a more reliable indicator of the thread size than an OD measurement over the thread crests. If the register is 1 3/8", then it would be difficult for the thread to be 1 27/64" (27/64" is bigger than 3/8" so the register would not go over the male thread).

If the register is close to 1 27/64", then further investigation is needed, including David's metric possibility. One way may be to do a three wire measurement of the thread. There is a good online calculator somewhere for this, whose address has been posted here before. It will tell you the best size wires, but will also give you the measurement if you input the wires you are using. This means you can use three drill shanks, three drill blanks or three bits of silver steel or whatever you have to hand that is close.

On further reflection, I am wondering how a loose fit of a 1 3/8" (female?) thread leads to the supposition that the mating (male, spindle?) thread is 1 27/64", a bigger size. Surely the only way to get the two threads to mate at all is some gender reversal?

04/02/2021 16:34:30

Surely the chuck does not use the threads alone for location. Does it not have a register inboard of the threads? The register size and fit of the chuck to that register is way more important than loose or tight threads. The threads do not want to be too tight lest they try to influence the register.

Thread: How to align a fixed steady?
04/02/2021 11:16:26
Posted by br on 04/02/2021 10:15:01:

How do you stop the fingers marking the material, just out of interest ?

One option is to use roller fingers. Small bearings can be used for this. Plastic bearings are also available. Wood turners use skateboard or roller blade wheels.

The trouble is that most steadies supplied as standard with a lathe are woefully small. I believe Hemingway offers a large capacity one and John Stevenson showed one made up of laser-cut steel sheets laminated together.

Thread: M2 x 2mm brass grub screws - do they exist?
04/02/2021 08:01:59

Make the balance weight 1mm greater OD (and remove material elsewhere if total mass is important).

Drill through hole in weight 1mm offset so one side has 3mm wall.

Thread: Loctite made in China?
02/02/2021 15:24:54

My starter for 2p. Genuine, grey import.

Thread: Tailstock turret
02/02/2021 12:30:07
Posted by ega on 02/02/2021 11:19:48:

I looked at your turret album. Your solution seems excellent for small diameter work, particularly if it could be combined with a five-way adjustable stop arrangement.

May I suggest an enhancement?

Right now, the length, design and position of the indexing plunger means the eccentric part of the turret has to be at the top or at the operator side of the tailstock.

If the plunger were rethought or relocated, the eccentric bit could be positioned towards the rear of the lathe, minimising potential for laceration.

Potentially, it could go perpendicular to its current axis. If it had a 45 degree end on it, pressing on a ball, the locking force can be made to turn the corner.

01/02/2021 19:20:16

I found a picture of it on AJ Reeves' site. It looks like only one part of it would need to change whether it had five or six stations. So perhaps keep your options open and buy two pieces of steel and make one of each number. While you are set up to make one, it is quicker to duplicate most of it than to start afresh if you only make one and it turns out to be the wrong one. If you use a 30-something when doing the dividing, it will cater for both.

Thread: Jacobs Chuck
01/02/2021 18:46:11

And run a file or stone around the snout to knock off any high spots before pushing it into the ring. Sometimes there are burrs there, especially around the three keyholes.

When you disassemble it, the nut will be in two pieces and look as if it is broken. It is made that way: in one piece with weak points and then split to facilitate assembly.

If you cannot find any visible cracks, and do not want to proceed straight to disassembly, make up a clamping collar to go around the ring, squeeze it up tight and see if the wheelspin disappears.

Possibly, you could repair it by drilling and tapping the outer ring for grubscrews. Rather than exerting pressure on the nut, which might not be a good idea, you might have to grind a dimple in the nut just so the grubscrew stops relative rotation of the two parts.

Thread: Bronze balls in place of steel balls in a Land Rover
31/01/2021 07:48:04

Rather than doing some kind of bush engineering on it, which is putting the cart before the horse, perhaps you should do some failure analysis first to inform your current situation.

How old is it? What service/lubrication/adjustment regime is recommended by LR? Has this regime been followed properly in the years since it was made? If you replace it as it was made and service it properly, what is its expected life? Is that expected life greater than your own?

Have a look at the range of available sizes for your proposed p-b balls. If it is being refurbished, will that be an additive process or a subtractive process? If the latter, slightly oversize balls, which are available in hardened steel may assist in tuning the steering to something slightly sharper than an oil tanker.

Thread: Metric thread sizes
30/01/2021 18:34:04
Posted by pgrbff on 30/01/2021 17:15:00:
...being in Italy with an Italian IP address my search results will be different to someone searching with a UK IP address.

This one any good?

https://www.bbpadova.it/viteria-e-bulloneria/barre-filettate/barra-filettata-passo-bsw-14010317/

30/01/2021 16:57:46
Posted by pgrbff on 30/01/2021 16:44:18:

I have been trying to find some high tensile 1/2 threaded bar in the UK and I haven't found any yet. It has rather a large 3 phase motor hanging off it and has bent.

If it has bent, it has been subject to bending forces.

Are you of the opinion that high tensile bar will resist bending forces better than low tensile bar?

The clue is is in the name. High tensile bar has a greater tensile strength than low tensile bar.

The ability of any structural member to resist bending forces is a function of its geometry and its Young's modulus.

Try:

https://www.grampianfasteners.com/product/653 (but shown as out of stock)

https://www.tfc.eu.com/product/high-tensile-threaded-rod-grade-en8-bsw/

https://www.ebay.co.uk/itm/BSW-Threaded-Bar-Screwed-Rod-Studding-S-C-Black-12-1-Foot-Long/191971076705 (admittedly, the grade is not shown, but it is hard to buy self-colour in anything but grade 8.8 so ask the seller).

Thread: Die query?
29/01/2021 09:52:15

Please have a read of these threads:

https://www.model-engineer.co.uk/forums/postings.asp?th=170639

https://www.model-engineer.co.uk/forums/postings.asp?th=170798

Thread: Milling machine enclosure
27/01/2021 18:45:21

As this is posted in the CNC sub-forum, can we assume it is a CNC machine that you wish to enclose (i.e. it will run unattended)?

I have something similar to this:

https://www.christowhome.co.uk/christow-large-reinforced-walk-in-greenhouse-1.html

with a CNC Taig mill inside it in a bedroom.

Cheap laminate flooring inside it, with the flaps of the greenhouse, shown folding outwards in the photo, folded inwards and under the floor. Henry inside for clean up.

Thread: Chester 836/Warco WM20 Lubrication Query?
27/01/2021 09:01:34

Like mini lathes, a lot of these machines differ only in their paint job and sticker name.

I have found that the US-supplied versions (JET, Grizzley, etc.) seem to have better manuals than our own.

Avail yourself of a list of likely manufacturers and then put 'xxx turret mill' into Google and look at images, where 'xxx' is the manufacturer name. That will help you find the model designation that manufacturer uses.

An original Bridgeport manual might also give you some pointers as the machines are close copies.

If you can find a suitable exploded diagram of the machine, that can help a lot with finding where to poke your oil gun.

Have a look at page 29. of this:

https://content.jettools.com/assets/manuals/690182_man_EN.pdf

Item 142 is the quill and it looks like half way up it is a drilling for an oil nipple, possibly for the lower spindle bearings.

If you lower the quill and smear with oil, it will come off the first time you retract the quill. Maybe lower it a little and introduce a thin oil from the top - it will be ground steel slowly sliding in cast iron so does not need much.

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

https://www.buvac.nl/wp-content/uploads/2019/09/HASPA.pdf

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.

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