Cutting threads on new arms for meddings.imp.-metric info

[Bm101]

Sorry guys. After some info and sage advice (as always).
I recently bought an old meddings drill. At first I was determined not to do it up. Determined I tells ya. Take the worst of the rust off and not get sidetracked yet again by doing up old tools. My resolve crumbled faster than a child's sandcastle with the return of the tide.

I'll just rub it down a bit I thought. When I found myself researching car body fillers I knew I was yet again a lost cause. If you've ever tried two part wood fillers and thought they went off quick... sheeesh! So Yeh. Learning curve as always. We're getting there though.

So back on track. Think I'm the only person on ukw who can send the thread off topic in my own first post.
Discipline. Must be disciplined.

The star wheel arms. Only one is original. All three are different lengths. Emailed meddings Typically awesome customer service tbf... No we don't do that part any more we can send you 3 new m12 metric arms. Nine quid odd each plus vat and travel. Ouch. Old ones are 1/2" about 12.5 mm and judging by what I can see from every other part on the drill are probably bsf.

Soooo... what I'm wondering is this.
If I get a length of mild steel 1/2 inch round bar. Buy a bsf 1/2" die and diestock I should be able to make my own? Can't be too tricky can it if I can keep the die square? Quarter turn back on each cut?
Bit worried the 2 new arms have been jammed in and messed up the thread but if it comes to it I can always tap out a bigger metric size and get some new rod. Worse case.

I'm away from home for a couple of days so can't measure tpi etc on the original rod.
I can get new balls for the ends in m12 so they should fit on ok with a bit of faffing.

Also. These ones look okie doke?
https://www.chronos.ltd.uk/acatalog/BSF ... _Taps.html

On the mobile. Internet services patchy.

Regards and thanks as always.
Best regards.
Chris

 

[MusicMan]

Yes, not too hard. Even easier if you have a lathe to keep things square. (you don't turn it on!).

 

[Bm101]

Thanks bud. Just wondering if I'm missing anything.

 

[AndyT]

Not too hard, provided you have a reasonable metalwork vice to hold the round bar vertical. Without a lathe, you'll need to file a short chamfer on the end. Then, holding the 1/2" bar vertical, bear down on it with the die in a stock and screw it on to the end. Take half a turn clockwise then half a turn back to break the chip. A few drops of 3 in 1 will help.
We managed it in school metalwork at age 11, under supervision.

Or I could do some for you if you like...

 

[Bm101]

Thanks Andy. I'll cope. Thanks for the heads up on the chamfer.

 

[Phil Pascoe]

Actually you could cut your bars a little over length and grind a longer taper, it's easier to start the die. Just cut the unwanted bit off the end after you're done. It's a bit easier to hold square.

 

[MusicMan]

BM101 - if you like I can do them for you, if you supply the metal and the die. I have the diestock, and a lathe with die attachment.

I was recently done a big favour by Droogs, who wouldn't take payment but asked me to "pay forward" a favour to someone else, so don't feel embarrassed about asking!

 

[Bm101]

Thanks Phil that's handy to know.

Many thanks MM, that's a really kind offer. Very generous of you. Actually quite like to try it myself first if you know what I mean.
If I mess it up I may well get in touch when I get back. In secret though so I don't disrupt everyone's perception of me as the ultimate engineer come woodworking God. :roll:
You lot need some one to inspire you after all... :-"

Thanks for all the help as always. Put my mind at ease while I think things through. Learnt a bit more on my little journey.
Chris

 

[AndyT]

A couple more tips for a first timer - sorry if these are too obvious.

Dies have a slight taper so start with the wider side towards the work. This is generally the side marked with the size.
For the first cut, use the grubscrew in the diestock to open up the diameter to the max, by tightening it into the split.
Afterwards, if needed, you can make a finishing cut down to exact size with the die closed up.
(Some cheap dies don't have a split and are not adjustable.)

 

[Bm101]

Not at all. Thanks again Andy. I had been wondering exactly that about split dies!

 

[AES]

@Bm101: +1 for all the points above, EXCEPT:

Andy T's point about which side the taper is on the die. Sorry, I don't want to contradict you Andy, and I'm NOT 100% certain of this, but I was always taught that the taper ("start") of the die is made on the side which is UNDER the die when mounted in the die stock - i.e. you can read the size, make, etc, etched/engraved into the TOP face of the die when mounted in the die stock, against the shoulder of the die stock.

SHORT PAUSE:

A short while later: I'm glad I wrote "I'm not 100% certain" about the above statement because the reason for the short pause is that I've just been downstairs to my cellar to check. I repeat I'm certain I was told the above is true, but now having looked at a random hand full of dies, various manufacturers, some split type, some solid, various sizes and various threads inc BSF, BSW, BA, and M (mainly "standard" though also a few M Fine), and was surprised to see they varied - some had the engraving on the "top" of the die, some on the "bottom", and would you believe, my flabber is well & truly garsted, one die had markings top AND bottom? "Well blow me down - gently" (or some such phrase)!

Anyway, the point Bm101 is, as all others have said, you do need to make sure you start with the tapered side of the die "downwards - i.e. this is the part of the die that first starts to cut the thread.

Having been taught to hand cut both male and female threads during apprenticeship (and having cut many many more since) I also fully endorse the need to make your own taper on the rod to be threaded. But do leave yourself enough length that you're not afraid to make the taper a decent length. If you're not filing that taper and have a belt sander, another good method is to twiddle the rod between your fingers while "turning" your taper against a not too coarse abrasive belt - ali oxide is ideal, but don't let the work piece start to discolour 'cos then you're making it too hot!

And don't be afraid to set your work piece in the vice as accurately as you can - there's nothing daft about using, for example, a small spirit level or square to check the work piece is set vertically in the vice, AND using the level across the die stock handles every half turn forward until you're well into cutting your thread. We were taught that it's easy to hand cut threads which have varying depths around the bar and which are "drunken", and that is too true - this was specifically checked by the instructor every time. But like many other things, once you've done a few it gets easier and easier (though still a task which needs care to guarantee success).

Good luck and hope the above is not too much detail. I'm obviously not the nearest one to you, but if all else fails I'll cut 'em for you.

AES

 

[chaoticbob]

If you happened to have a drill press to hand :wink: together with one of those vices with a vertical V in the jaws on the table, you could stick the new arm in the vice and through a hole in the drill table then use the nose of the drill chuck against the back of the diestock to get you started square. Rough and ready compared to doing it on a lathe, but better than trying to start the thread freehand.
Rob.

 

[MusicMan]

Many thanks MM, that's a really kind offer. Very generous of you. Actually quite like to try it myself first if you know what I mean.
If I mess it up I may well get in touch when I get back. In secret though so I don't disrupt everyone's perception of me as the ultimate engineer come woodworking God. :roll:

That's fine, I thought you might say that. And I promise not to tell if you do get back .

"Cut a man a thread and he can screw it up once. Teach a man to thread and he can screw it up for life" !

Oh one other thing, as has been said some cheap dies don't have a split. I use a Dremel with a hard abrasive blade to cut a thin split. Works fine.

Don't be tempted to use stainless steel, this is much tougher!

Keith

 

[DTR]

I've only just seen this thread..... I can't contribute anything to the excellent advice given in the posts above, but I'll offer my assistance along with the others should you want it

If you happened to have a drill press to hand :wink: together with one of those vices with a vertical V in the jaws on the table, you could stick the new arm in the vice and through a hole in the drill table then use the nose of the drill chuck against the back of the diestock to get you started square. Rough and ready compared to doing it on a lathe, but better than trying to start the thread freehand.
Rob.

^^^^ This is a really good tip if you have no other means of starting the thread square.

 

[Bm101]

More advice gratefully received. You guys really are legendary in your willingness to help and advise a beginner. Ukw is quite a special place really. As always I'm left a little stunned by how much members are willing to help some numpty like me. Anyway enough of all that.

Aes. Thanks for the detailed reply. I have a little cheapo but much loved inherited clarke belt sander with a few varieties of oxide belt. When I made/converted/bodged my little stanley 101 'infil' I quickly learnt I couldn't reliably turn the tip of the cap screw to a point (a brass m10 bolt with a salvaged plumbing pipe cap smashed onto the head) by hand. I got round it by drilling a 10 mm hole on a bit of wood and using it as jig of sorts to spin the bolt against the belt. Will do the same for the bar to chamfer it.
Bit of fiddling but should give me a decent start with any luck.
I bought one of those gem digital meters second hand from Karl on here a while back for a cracking price. Planning to square up the rod in the vice as well as possible then whack that baby on the diestock. If I can't get it square with that after a practice run or two I don't have any business doing this stuff tbh...

Chaotic Bob. Great tip! Many thanks. Storing that one up. I could restore the drill and then come back and do the arms, only reason not to do it is the paint job really. Details!

Keith. Thanks for understanding. :wink:

Dave. STOP. Thanks mate. STOP. Running short of raspberry jam. STOP. Kids starving. STOP. Situation desperate. STOP. Please inform Doris . STOP.


I need to get home, get the replacement arms out and check the last owner didn't bork the threads in the star wheel jamming in wrong size threads. If he did I'm going to need to tap them out and then go metric anyway.

Cheers chaps. Your help is much appreciated. Regular readers of my drivel will realise where I am and my lament at the closure of the colyton tool shop. What sort of luck to find a place like that only for it to shut down 2 months later....
Cheers as always.
Chris

 

[Bm101]

Sorry to go on...
Just had a thought. Would I be okay to use aluminium bar instead of steel? 1/2" should be strong enough shouldn't it? Easier to cut and less prone to rust.
Thanks.
Chris

 

[AES]

Can't see why not Bm101. If you have a spare piece (i.e. don't have to buy it) and can feel roughly how much force is needed to lower the quill (against an object being drilled) just put your piece of bar in the vice at approx the required length and reproduce that force. If the ali bar bends then it's not strong enough!!!! But I doubt that will happen. It should be fine.

Then if going ahead to thread the ali bar, be extra careful to clear the chips VERY regularly as the die cuts down the bar. Ali swarf is "sticky" and will tend to clog the threads on the die. Because the ali bar is soft, bits of swarf stuck to the die threads will tend to produce badly cut threads in the bar if you don't clear the swarf regularly.

HTH

AES

 

[Bm101]

Thanks mate. Much appreciated. Wondered if the ali might be easier to polish up bright as well tbh.
It's a bit cheaper too. Never hurts.
Found this mob who seem reasonable. https://www.forwardmetals.co.uk/product ... d-bar.html
Will make a decision when I get back.
Picking up a few bargains on ma holibobs has become a bit of a tradition. This year though.... Nothing. Literally not a thing. I even popped into Axminster HQ and wandered round. I kicked a few of the hobby range drills grumpily. Watched a middle aged fella asking daft questions about lie nielsen planes while his wife hovered. Meh. Took a soba die stock out its box then put it quietly back on the shelf. I could make a better one myself. Felt oddly empty.
Few hours later I'm mooching along and I see a couple of decorating tables set up outside a chapel. Bric a brac. Tosh. Stuffed toys, knitwear and two yards of bad china.
Ffs.
'Don't s'pose you have any tools hidden away there do you?' I ask the comically genial volunteer. 'Well I don't think so....' he answers brightly. He ducks down and has a shuffle in the boxes. 'I don't suppose these are any use? It's all we have I'm afraid.

Pulls out a twin screw metal working clamp, what I'm guessing is a sorby paring chisel in reasonable and a tap and die. Just the two.
Shut the front door. It can't be. 1/2" bsf both of them.
Sometimes, just sometimes, you are sent a message. :shock:
Best to answer.

Best as always.
Chris.

 

[chaoticbob]

A couple of thoughts on using ali...
A rule of thumb is that ali is about as strong as steel on a weight-for-weight basis (the Youngs modulus for ali is about one third of that for steel, but it's about a third the density), so you will derating the stiffness of the arms by a factor of about three. If my calculation is right(!?) it would be like replacing the half inch arms with 0.28" in steel. I assume Meddings would have specified the thickness of the arms to match the strength of the machine - you don't say what model it is, but it sounds like it's fairly beefy and potentially capable of serious work.
Second thought is that aluminium is much more prone to repetitive stress fracture than is steel. I'd worry that the arm will eventually break at the point where it enters the hub, where the stress is at it's highest. Being threaded at that point, the thread 'valleys' will concentrate the stress too.
Well, that's the theory, but I found a bit of half inch ali bar in the scrap bin and tried it in my Fobco instead of the steel bar (this machine has a single hole drilled diametrically through the 'hub', so no threading necessary) and bore on it at a distance of maybe a foot from the hub with a bit more than the force than I'd need to drill a half inch hole in steel. It flexed noticeably, but no permanent bend that I could see.
Personally I'd stick with steel.
Good luck with the restoration whichever way!
Rob.
PS - you're going to trip over a length of half inch steel in the street next aren't you! (Crossed posts).
R.

 

[Bm101]

Ok thanks Bob. That's a definitive answer! Steel it is. Many thanks for going to all that trouble with your drill to test it as well. Above and beyond and all that. It's really much appreciated. Mine's an m4b btw. There's a few pics here. new-meddings-owner-if-i-ve-learnt-one-single-thing-t106700.html

A link to the surprise holiday haul
https://imgur.com/OaEW26v
Looking more closely I think the chisel is not a sorby. Handle fooled me. I can't make it out without a bit of a clean.

Thanks again .
Regards
Chris