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

[AES]

@Bm101:

There's nothing to disagree with in chaoticbob's post, on the contrary, BUT, a lot will depend on what "sort" (alloy) your ali is - some is pretty hard and will work-harden if it's bent regularly - that's just one example of "fings what can 'appen".

All the same, personally, if I had a suitable ali rod to hand, and didn't know it's spec (alloy type), I'd still give it a go, but your choice of course.

All that happens at the worst is that it will bend and then (probably) slowly break, meaning you start again using MS the 2nd time.

IF you do try ali, as well as my warning about "sticky" swarf above, DO use lubricant while threading. The books say paraffin, but if none available, I've found WD40 works as well.

Whatever you choose, good luck.

HTH

AES

 

[MusicMan]

Me I'd use a bit of nice ground steel bar stock from Cromwell's. It would look cool and match all that nice work you've done on that Meddings.

 

[Bm101]

Thanks Aes. As always I appreciate your detailed advice. The supplier link I posted was the cheapest I could find for graded ali. 6082 T6 which seems to be the most suitable for purpose.
I think you're right. I'd even read about it work hardening as you mention. I do try to do my research before asking daft questions, sometimes I just end up in the proverbial cul de sac...
If had any in my shed I'd try it first. But seeing as I will have to buy either option the steel seem the right option.
It's all good knowledge and handy to know so thanks again for sharing. As always it's much appreciated.
Regards
Chris

 

[AES]

Glad to try and help mate. Loads of people help me on here.

As a point of interest, musicman obviously "knows his onions", but I think it's arguable about the use of ground steel bar stock - it would look nice, no doubt. But as you've said you've not cut threads by hand before, it's arguable (either way) if it would be easier to start off thread cutting on a "soft" bar or a "hard" one!

But if you've got to buy the stuff anyway, then go ahead, buy steel - you KNOW that'll do the job.

AES

(Don't forget, pix when finished)

 

[Bm101]

Tbh, I had a look but couldn't see it on Cromwells site. (I'm not at my pc btw so it's a bit painful ) I've used ground flat o1 stock a couple of times to make a few bits like plane irons etc. I'm not sure what the difference is between that and mild steel. Only stuff I could find on Cromwell on patchy mobile Internet was flat bar.

Edit: Scrub that. Bit more research done this morning.

 

[Bm101]

Riiiiiight. Another daft question. Soz. How do we hold round bits of metal securely in a vice?

So the bright mild steel turned up Friday following closely on the heels of the 1.5" diestock. Had a moment the other day when painting bits of the drill where I was struck by the thought that the 2 replacement arms had quite possibly borked the internal thread on the star wheel. I'd picked up the 1/2" tap with the tapered die but that won't get to the bottom of the holes I realised..... Can you see where this is going yet? I thought very very briefly about taking a hacksaw to the tap. Very Briefly lol. Sod that. HSS. Bit more enquiring of mind and I realised in the whole history of engineering this problem had possibly been faced before so toodled of to the internet. One visit to ebay and a few days later a half inch bsf bottom tap turned up. (SunnyBob I can hear you laughing you monster.)
Had a day off today and a couple of hours free. Crack on I thought. Should give me enough time to get the arms sorted.
Cleaned up the internal threads with said bottom tap. Then did some measurements and cut the first length of steel. Looked at it and realised I'm a bit of a div and cut a bit more off. No idea what happened there. Shhhh. Used it to cut the last two. Found a squareish bit of off cut to use as a jig and drilled a hole in it. Looked at it and realised I'm a bit of a div and went and got the right size forstner bit and drilled the right size hole in it. Shhhh.

Chucked em all on the Clarkey.
Action shot! Woooo!

Going good guns.
Being very careful to try and stay square I started cutting the thread. Realised the rod was turning in the vice despite turning the diestock back as much as I could to reduce force (I have some magnetic rubber jaws on it.). Cinched it up as tight as I could and same thing. You can see the effect on the rubber jaw below. Wrapped it in leather and tried with and without the rubber jaws. Nope. Nearly tried just masking tape then thought better of it. I'm really trying to avoid messing up the surface of the rod if possible to save extra work. Had a think and wondered about a coupla things. What about using wet and dry? Then I got to really thinking about surface areas. If I could make it grip on 4 points instead of 2.... V blocks. I don't have V blocks but wondered about getting the router out. Time was getting on so I didn't attempt it without asking advice but has anyone tried this with some hardwood? More trouble than it's worth probably. I'm sure there's a solution that's easier that I'm missing! Already started to mark the first rod.

Any ideas for this noob? Would just a bit of cardboard etc work? I lost patience and came in and poured a cider at this point before ruining anything.
I even tried using the mistake off cut of rod to balance the vice jaws in case it was racking to no effect.
:|

Cheers!
Chris

 

[AES]

Quick suggestion - "make" a couple of wooden blocks with a v grove in each, sized so that they will NOT QUITE close on the bar (bit of trial and error required) as you tighten the vice. Should work.

Tip for the future - "next time" you break a taper tap ("What next time I hear you ask?" ) don't just chuck the broken tap in the bin (it'll probably "only" be broken at the bottom, tapered, part). Instead grind the bottom off square and hey "Presto" (sorry!) one plug/bottoming tap next time you need one.

AES

 

[AES]

Quick P.S. to the above, first part - the wooden blocks should be at least the length/height of the vice jaws, if not more - NOT less.

 

[Bm101]

Many thanks as always AES. You are a Gentleman and a Scholar. Was kinda thinking today maybe the m12 arms from Meddings would have just saved a load of grief. Wedge them in, job done. Probably spent close to the cost to make my own. #-o
But then, that's not the point is it.

*cries into cider.

 

[MusicMan]

I can't quite see whether your die has a slit in it. This should be lined up with the centre grub screw and tightened up like mad to wedge the die open for the first cut. Lubricated of course. Then you can close it up on subsequent cuts. This will be MUCH easier. In fact I did one this week where I didn't have a big enough die holder, so I held the bottom of the die in the vice and wedged it open with a screwdriver . Couldn't turn it at all without opening it. This was extending an existing M10 thread in a fairly strong bolt.

If it doesn't have a slit in it then make one. A Dremel with slitting wheel or the like will do it.

With a shaft this size you don't have much hope without using the die "progressively".

Keith

 

[TFrench]

I've used some thin aluminium to keep vice jaws from marking work in the past. AES's way is right of course. If you have a 52 1/2 vice with wooden jaws, that'll work too.

Brainwave - you could drill an appropriate sized hole in a block of wood, then cut it in half to get your "V" blocks. The kerf will give you a gap.

 

[Bm101]

Point taken Keith. It has a slit.
I got the idea but not the necessity. That makes a lot of sense. Didn't realise I had to be so aggressive with the screws but itsvery obvious once pointed out.
Many thanks
Chris

 

[Bm101]

I've used some thin aluminium to keep vice jaws from marking work in the past. AES's way is right of course. If you have a 52 1/2 vice with wooden jaws, that'll work too.

Brainwave - you could drill an appropriate sized hole in a block of wood, then cut it in half to get your "V" blocks. The kerf will give you a gap.

Brainwave is right. That's genius. (hammer) Thankyou.

 

[AndyT]

A handy source of thin aluminium would be a can of cider, unless your preferred brew comes in stoneware jars...

 

[TFrench]

I've used some thin aluminium to keep vice jaws from marking work in the past. AES's way is right of course. If you have a 52 1/2 vice with wooden jaws, that'll work too.

Brainwave - you could drill an appropriate sized hole in a block of wood, then cut it in half to get your "V" blocks. The kerf will give you a gap.

Brainwave is right. That's genius. (hammer) Thankyou.

Sometimes I surprise myself! :lol:

 

[Bm101]

Thanks Andy as always. That's a good call. My cider comes in 20 ltr cardboard bagging boxes unfortunately. On a pallet.... :-"

 

[Phil Pascoe]

If you could find threaded rod the correct size you could sleeve it between the "axle" and the knobs.

 

[Bm101]

Cheers Phil. Inventive approach. Hopefully using Musicman's advice and better grip in the vice I will be okay. Id assumed first stage cut was already open on the die. I didn't realise I had to actively open the die. Sounds daft now that I didn't think of it really. I'd assumed it was there to keep the die in the stock before using the other screws to tighten for a second cut. What else could the screw be there for. Live and learn eh? Away with work for a couple. Will post results when I get back.
Thanks all, as always your time and advice is much appreciated.
Regards
Chris

 

[Bm101]

Annnnnd it goes on....

Tried Andy's ali can. No joy.
Next step Mr French's novel approach.

Nope. Still turning.
Tried both, wrapping in ali within the 'brace'. Nope.
Tried wrapping several times. Nope.
Tried with the false jaws and above. Nope.

I'm at a loss. Wondering if it might be the vice. Trying not to blame my tools but....
Packed up today in frustration and came in and that's very unusual for me.
I tried packing leather in the hole, all sorts. Soon as I get any resistance it turns. Gaaaah!
Starting to think about taking up MM's kind offer to do it on the lathe. :|
The first rod has become a practice rod because I've borked it, thread is cutting okay if i could keep it still but the shaft is marked up. I have just enough left to make one more.



Chris

 

[Phil Pascoe]

File two small flats on the other end. If you're going to put knobs on them the flats would be inside the knobs, and wouldn't matter.