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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: Another - What is the correct name for this
03/12/2019 19:29:22

The thing that immediately comes to mind seeing your sketch is a planer gauge. As the name suggests, however, it is a measuring tool and not really designed for workholding.

Thread: Meddings LF2 pillar drill
01/12/2019 08:16:15

Any Meddings will be a good drill, so long as it has not been totally abused.

As JohnF says, the deciding factor may be whether it has a single speed or a two-speed 3-phase motor.

A single speed motor is relatively easy to convert to 230v three phase and run from a VFD, even if you have to dig out the star point of the motor.

The eBay link is single speed motor (see photo of the name plate - two speeds are given but only because of different power grid frequencies).

A two speed motor is very difficult to convert to lower voltage operation.

Thread: M24 x 2 arbour
28/11/2019 08:38:51
Posted by Emgee on 27/11/2019 22:00:28:

Get yourself a blank end MT2 arbor and thread it in the lathe.

All the boring head arbors I have seen are flanged after the thread, to stop the head screwing itself into the spindle. Finding a MT2 blank arbor of big enough diameter to accommodate this may prove challenging.

Thread: Tailstock indexing
24/11/2019 20:54:38

See:

https://www.model-engineer.co.uk/forums/postings.asp?th=140386

where a graduated Myford LEADSCREW handwheel is repurposed for use on the tailstock.

Thread: Acme thread
24/11/2019 08:30:53
Posted by Shaun Belcher on 24/11/2019 00:17:30:

Myford claim its 10TPI for the imperial feedscrews, but only say the metric ones are 3/8" 2mm pitch.

I think what this means is that the outside diameter of the screw is 3/8" but the pitch that is cut on it is 2mm.

Basically a metricated version of the imperial screw, the only change being the distance between the thread crests. It means all the stuff at the handle end will fit unchanged.

Thread: Myford Super 7 Metric thread cutting gears
24/11/2019 07:55:14

Until someone more qualified comes along, please have a look here:

https://www.model-engineer.co.uk/forums/postings.asp?th=125630

as I think it will answer most questions.

Thread: Operating manual for a Harrison 140 metric lathe
12/11/2019 14:52:22

Type 'Harrison 140 imperial threading' into Google.

Inter alia, it will find

https://www.mig-welding.co.uk/forum/threads/gear-cutter.56392/page-2

and

https://www.mig-welding.co.uk/forum/threads/advice-on-lathe-purchase.62989/page-3

These may shed light onto your problem.

Most unlikely to have a 6cm leadscrew unless it has come from a dressmaking shop or is ex-Blue Peter.

Thread: Drilling big holes (in tiles)
09/11/2019 18:49:49
Posted by JasonB on 09/11/2019 16:28:43:

Use it to drill a hole through some 6mm ply or MDF then hold that against the wall to guide the holesaw until it has started the cut

Holding the guide in place is not easy, especially on a slippery tiled surface. If time is not pressing, glue the guide on 24h in advance using hot glue or silicone.

I agree with the others that a small hole is all that is necessary. With a bit of careful measurement, you can drill on centre of the tap, expose the screw holding the handle on, remove the screw and handle and use a square socket on an extension to turn it. Remember when finished not to leave it fully open.

Thread: INT30 sensitive drilling attachment
09/11/2019 13:55:13
Posted by Mark Davison 1 on 09/11/2019 09:38:15:
The bit I still cant picture, even after study the drawing you sent (thankyou) is which way up the adapter mounts to the nose. I'd have assumed the ground face mates with the nose but the assembly drawing suggests it goes the other way, with he ground face down?

Sorry, I thought I had added a note on the email. The assembly drawing is incorrect, my fault. The ground part is up, the counterbored holes are down.

To me, it is an easy part to reproduce, needing precision only on two concentric bores, one for the spindle nose, the other for the ER holder.

Thread: Boring bar toolpost.
03/11/2019 16:31:48

This may be a wildly foolish idea, but if there is any uncertainty over deflection, could you put gussets under and behind the bar?

How much is there between the outer face of the bar and the point of the tip? You could shrink or loctite on a sleeve that increases its effective diameter. Even an eccentrically-bored one so that the under and back get more meat than the front.

Thread: INT30 sensitive drilling attachment
02/11/2019 08:46:19
Posted by old mart on 01/11/2019 21:14:15:

Its a difficult project, what with the core diameter of the pull stud being only 9.85mm and some method to allow the chuck shaft to move axially and turn with the toolholder via a keyway or similar. The stroke will be severely limited, if the whole assembly is not fairly long.

These sidelock spindles may have the answer to the finish of the bore and the screws could drive a slotted spindle.

**LINK**

The sidelock holders do project downwards so a bit of headroom is lost.

Your idea of a boring head shank is very good. They are unlikely to be through hardened and a nose cap could be used to hold it into the spindle, thus eliminating the troublesome drawbar. Think Myford spindle nose MT2 collets. Cut the top off it as necessary as the full length of the taper is not needed for axial drilling loads.

You could use the threads originally destined for the boring head to screw on an unhardened piece that provides the sliding drive system.

Was is Erikson who did a quickchange toolholding system for Bridgeports that used a cap to retain the tooling instead of a drawbar?

In practice, stroke length is limited by lever ratio at the top end. 6:1 ratio, for instance needs lever to go 300mm for 50mm quill travel.

Edited By DC31k on 02/11/2019 08:48:51

02/11/2019 08:37:07
Posted by Mark Davison 1 on 01/11/2019 20:35:05:

I was hoping to use at least some of the depth of the INT30 taper so as not to loose too much of the available height.

Using a spindle nose cap, it can project upwards into the taper to give the height and length for support, but does not need to be machined to fit the taper.

31/10/2019 16:42:49

Have a look at how Schaublin do their sensitive drilling attachment for the 30 taper spindle on the 13 mill.

It locates on the spindle nose itself, like a big facemill would.

Much easier to make than something that locates in the taper.

You need to think of how the drive will be transmitted while still allowing sliding movement. Generally done with a key and keyway. A dog point grub screw into the 3MT adaptor could be used, but requires tapping a hard part. An accurate keyway is equally difficult in a hardened ER straight shank chuck.

Copying the Schaublin design would allow you to put keyway in unhardened spindle nose adapter and use angle grinder to form a not-very-precise-over-wide slot in ER chuck and then JB Weld in a key (using the adapter to keep it aligned while it sets).

See bottom left of page 6 here:

https://drive.google.com/file/d/0Bxr59DtuJda_amx1V1dvNE8xVXM/view?usp=sharing (Anglo-Swiss Tools, Schaublin 13, French catalogue)

for nose dimensions. Top right of page 12 for attachment complete.

I have a drawing for all the Schaublin parts so if you PM me with contact details, I can send to you.

Thread: Additives to kerosene for degreasing?
30/10/2019 19:48:28
Posted by Mark Rand on 30/10/2019 16:48:55:

If I were braver/more informed, I'd probably find a suitable detergent to add to straight kerosene.

If you look at the MSDS here

https://www.img-limited.co.uk/wp-content/uploads/2015/01/Blue-Jet-Degreaser-CLP-MSDS-Sheet-FULL-1.pdf

it is just kerosene with IPA (propan-2-ol) and a bit of ethoxylated oleic acid (which is a fairly generic non-ionic surfactant).

This is one of the few data sheets I found that actually list the minor ingredients; most others just say 90% kerosene and stop there.

Thread: SHAPER ACCESSORIES
29/10/2019 19:41:22

Ian Bradley's 'The Shaping Machine' contains drawings for a small and large hacksawing tool (pages 41 & 42). Rather smaller that that shown above.

The NEME-S website (http://www.neme-s.org/) has an online shaper reference section.

Thread: Tools of unknown types.
29/10/2019 07:02:28
Posted by John Reese on 29/10/2019 00:41:46:

There a lot of similar collet chucks on the market. They are definitely not ER type collet. They resemble Acura grip or TG collets but my not be compatible with either system.

I think the ones shown are known as Oz collets.

Thread: Buying a Propane Torch
28/10/2019 19:25:31
Posted by Andy Carlson on 28/10/2019 17:54:56:

I don't want to start paying for those medium sized gas cylinders that hang off the bottom of the next size up handheld torch so my thinking is to skip a step and go for something with a hose that can run off the same propane cylinder that I use for the BBQ.

I do not know if this will be germane to your issue, but it is something I only recently discovered: Rothenberger, I think, make an adaptor that screws into the torch that the medium-sized cylinders hang off and allows it to run off a standard propane cylinder via a hose. If you have one of these torches already, it gives you the best of both worlds: cheap propane gas on a tethered torch and 'cordless' MAPP on the disposable cylinders.

Thread: Boxford metric lead screw fitted to imperial lathe?
28/10/2019 19:15:36
Posted by Brian Wood on 27/10/2019 18:37:09:

You have the right idea, but what DC31k has omitted to say is that the driver on the spindle (after the reversing gears) will be 20T and the gearbox entry spindle needs a 56T gear in all cases.The change gears are fitted in the chain linking those two.

Sadly, and I hate to have to point it out, but there is one error in his table in the listing for 1.75 mm pitch. The change gear ratio should read 7/8, which could be 35/40 as you have interpreted the ratio.

Thank you for the clarification and correction.

I am glad that it has been peer-reviewed and the bugs worked out so speedily.

I think I was a bit wooly in my terminology when I used CG for change gear ratio: it should have been more closely defined as change gear ratio modification to standard ratio (thus, when it is 1/1, there is no modification to standard/factory needed).

The incorrect 4/7 came about as I started off with 7/4 and 24tpi (i.e. gear up 1mm pitch to get 1.75mm*). That needed an extra 20t wheel added to the set (35/20). To reduce required number of change wheels, I realised you can gear down 2mm pitch but did not do well in changing the numbers. It is fortuitous that the correct 7/8 or 35/40 can come from the existing set.

Brian's calculations on getting you imperial pitches are to be highly commended.

Maybe it is bad form to recommend a different author, but Martin Cleeve's Screwcutting book is essential reading. He spends a good bit of time talking about non-standard leadscrews (mainly for speed in production work).

* And if anyone has an imperial Chipmaster, that is how you can get the missing 1.75mm on this machine, with a 63/36.

27/10/2019 11:22:52
Posted by JasonB on 27/10/2019 10:09:26:

Well I can get the 100/127 to work as 100/127 x 3.175 = 2.4999997 so near enough 2.5

but when it try 135/127 x 3 I get 3.1889763 not 3.175

Unless I'm doing it wrong.

We should keep firmly in our heads that we are discussing machines with a (Norton) gearbox. The ratios in the gearbox of a native imperial machine will be different to those in a native metric machine. The imperial Boxford above is a good example - it has, for example, a ratio with an 11 in it. You would not find a native metric machine with an 11 in its gearbox.

[Interestingly, it has a 23, half of which is 11 1/2, used for American pipe threads but not UK ones and does not have a 19 which we do use. Uncle Tony's site says it was a copy of the US South Bend and this is very apparent here].

The difference in gearbox ratios affects our choice of translation gear, so a gear to go from imperial to metric on an imperial machine will differ from that used going from metric to imperial on a metric machine.

If I might say so, there is no place whatsoever for decimals in any discussion of screwcutting. To avoid confusion, fractions are the only acceptable currency. One inch is defined as exactly 25.4mm, or 254/10 or 127/5.

Thus our 8tpi leadscrew has a pitch of 1/8" or 127/(5x8) = 127/40 mm. If we drive this with a 100/127 combination, the 127's cancel and we get 100/40 or exactly 2 1/2mm .

This is where use of decimals and a calculator lets us down. With fractions, you can see the numbers and you know that the 127's must cancel, so you know that one side of the multiplication sign has to have 127 as numerator and the other side of the multiply sign has to have 127 as denominator. If you have a 127 gear, the conversion will always be exact. If you come to a place where it seems approximate, you have taken a wrong turn somewhere.

Now onto our 3mm pitch leadscrew and our 135/127 gear. 1mm is 5/127 inches. 3mm is 15/127 inches. 15/127 x 127/135 gives 1/9 inches exactly. So our 3mm pitch leadscrew is behaving as if it is 9tpi. This number seems strange at first sight, but it probably combines better with the metric-native ratios in the gearbox to give the required imperial pitches.

27/10/2019 10:38:03

OK, assuming it has the same gearbox as that shown at http://www.lathes.co.uk/boxford/page7.html BUT with a 3mm pitch leadscrew, the following should work.

mm is metric pitch required. TPI is gearbox setting. CG is change gear ratio. Only needs 35, 40, 45, 50, 60 and 70 gears with one duplicate. Best to copy and paste somewhere using a monospace font.

mm TPI CG
3.0 8 1/1
2.5 8 5/6
2.0 12 1/1
1.75 12 4/7
1.5 16 1/1
1.25 24 5/4
1.0 24 1/1
0.9 24 9/10
0.8 24 4/5
0.75 32 1/1
0.7 24 7/10
0.6 40 1/1
0.5 48 1/1
0.45 48 9/10
0.4 48 4/5
0.35 48 7/10
0.3 80 1/1
0.25 96 1/1
0.2 96 4/5

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