Thread: Making a Drawbar

The drawbar for my Hercus is exactly the same as the lower one in Vernov's picture.

I soon learned not to over-tigten the drawbar on the ER40 collet chuck. I just hate the idea of those shock loads on the bearings. I can usually get away with one sharp rap with a plastic hammer, but still...

I thought about buying a Hercus spindle nose protector and using it as a "pusher" to push the collet chuck out from behind. Anyone tried this?

Originally Posted by Pete F

Can't criticise what you did at all Bob, and from what you said, if I had the same material laying around then I would have done exactly what you did. My point was to suggest that if someone was going out to buy material, I wouldn't pay the significant premium 4140 attracts as it's quite a lot more expensive in my experience. I deliberately leave my drawbar threads soft so there's no chance of galling on hardened tooling and allow them to yield a tad.

I hear you re 12L14, I have some a few parts of a high speed head that I think they used something like that and it's a complete PIA as I'm forever chasing rust off it. It's probably less an issue for something like a drawbar as it's not really exposed to the environment and lives inside the spindle, but I think your cautions about using material prone to rusting are very valid.

It's ironic this is coming up now, as I MAY have to make a new W20 drawbar (actually a draw tube) to suit my lathe. I hope I'll be able to repurpose an existing one, as I don't have an internal W20 thread tool ground, so a simple exercise becomes a PIA.

Hey Pete,

If you had acquired a 102 which accommodates W20s, along with a variety of other collets, I'm sure you would have let me and a number of others know so I'm assuming the drawbar is for the 260. I'm keen to find out what you are up to.

As far as the 4140 goes, it was a length of PG bar I had intended using as a replacement arm on my Lotze hacksaw. I don't use the Lotze because you made me buy a 4 x 6 bandsaw so the bar became far more useful and used drawbars.

I do use 1045 probably more these days than 4140.

Bob.

No 102 here Bob. I turned down the MT3 taper on a Wohlhaupter head and will shrink a W20 dedicated tool holder on it. Getting everything concentric, although not actually required in this case as it's a single point tool, was made more difficult by not being able to put a W20 collet in my lathe. Soooo I decided to make an adapter, and here you see the 3D printed prototype I'll fiddle with before committing to cutting metal. For some reason the photos I take make these 3D prints look absolutely dreadful, but in fact they have a texture to them a bit like a really rough cut turned piece. I look at that photo and just cringe at how bad it looks, however you'll just need to turn a blind eye to that and take my assurance that's the camera (light angle??) doing that, and it's in fact not too bad. This was printed in ABS and that finishes beautifully smooth if I subsequently machine it. I will turn this piece to confirm no nasty surprises and it could probably be used just as it is for occasional use. The advantage with plastic, especially ABS, is that it has some give in it that conforms to imperfections better. It means both finish and the actual accuracy aren't as critical as if it were say hardened steel, as the average of errors principle takes care of overall accuracy. That has 20% infill so wouldn't be especially strong, but more than enough for testing.

IMG_0014.jpg

All this talk about draw bars/draw tubes has made me realise that I may have to shorten up my MT4 adaptor in order to get the drawtube in there, but that's the beauty of just printing it off first and fiddling with it in the virtual/plastic world.

4140 for a draw bar for this application is not going to break anybodys bank account, even the pensioners.

Originally Posted by pipeclay

4140 for a draw bar for this application is not going to break anybodys bank account, even the pensioners.

Cannot buy 4140 or any higher tensile steel in under 16mm size in this area... They simply do not stock it..

Originally Posted by pipeclay

4140 for a draw bar for this application is not going to break anybodys bank account, even the pensioners.

Maybe not, not for me to be the judge of what others can or can't afford, however you specifically stated this.

I would not be using mild steel for the draw bolt/bar.

I'm curious as to why you specifically state that you would not use mild steel?

Wish i knew something about steel etc. If know for sure what everyone is talking about and if someone is taking the mickey

Dave TTC
Turning Wood Into Art

Originally Posted by DaveTTC

Wish i knew something about steel etc. If know for sure what everyone is talking about and if someone is taking the mickey

Dave TTC
Turning Wood Into Art

Yes Dave I believe the middle third of this thread was the blokes having a lark about over the top to ludicrous suggestions for steel type and methods one upping the last . I think it stopped about post #24.
Before and after that is some reasonable discussion.

Really not much different to wood in that regard. Different steels have different alloys added to them to change the basic iron's properties and make the material better suited to different purposes. Just as pine would be a poor choice for, say a marine prop bushing, so would some steels be better suited to various duties. 1020-1040 etc are all low carbon steels and may be thought of as the "pine" of the metal world. The 4140 is a high tensile steel and 12L14 is a free machining steel that machines much easier than say 1020. Black bar is just the crap left over in the bottom of the pot after they're done cleaning it out

A bit off the OP topic but relevant to the current topic, how expensive is 12L14 and is it the same stuff that Tubal Cain talks about?

Ben.

Originally Posted by bwal74

A bit off the OP topic but relevant to the current topic, how expensive is 12L14 and is it the same stuff that Tubal Cain talks about?

Ben.

I don't think they had 12L14 in biblical days

mrpete222 then....

Thanks Pete. The learning curve begins

Dave TTC
Turning Wood Into Art

Oh and when i first saw the title of this thread I thought someone was talking about the front 'A' frame for a trailer

Dave TTC
Turning Wood Into Art