Hi guys - I was wondering if anyone has successfully made any Lovejoy style motor couplers - the complete couplers seem to be about £15-20/$30-$40 over here in the UK, which seems like a hell of a lot for 1.5" of 1" alloy rod and a synthetic rubber disc.

I have seen the rubber bits for about £1.50/$3 so I am tempted to try milling out the alloy parts - I'm guessing that as long as I make the metal slightly too big, the rubber part will compress to soak up the imperfections without inducing bucket loads of backlash. Or is there a reason they're so expensive?

Cheers.

I work with a guy that made them all the time on a cnc at work. When they would need them in the shop he would cut the end peices out and they would order the spider(rubber peice). It shouldn't been an issue if you have access to a mill. If you are making them on an manual you may want to be sure they are ballenced when you are done. It may not affect your appliction though.

HTH

AC

I don't know how these came to be labeled 'Lovejoy' couplings,:confused: LoveJoy make about a dozen very different styles of couplings, they are closer to being Olham couplings.
Even Lovejoy themselves call them THIS.:)
http://www.lovejoy-inc.com/miniaturecouplings.htm
Al.

I don't know how these came to be labeled 'Lovejoy' couplings,:confused: LoveJoy make about a dozen very different styles of couplings, they are closer to being Olham couplings.
Even Lovejoy themselves call them THIS.:)
http://www.lovejoy-inc.com/miniaturecouplings.htm
Al.

Lovejoy started out with the jaw style in industry, hence like crescent all adjustable jaw wrenchs are now "crescents". Oldham was the other hence oldham, the main reason for the aparent expense is that they are case hardend in alot of cases. Also the spider is made from propertiery material or so they say. One nice thing is that they are not matched, in my trade thats a bounus I can take a motor off leave the coupling on the shaft set another motor up use that coupling as a guide and as long as the spider is good then they line right up. I dunno for me, 3-5 hours of work or ordering it and putting it on without tweaking, my time is spent doing more important things like pleading with my wife for more space. In the sates they run around $40-$50 type dependant. Let us know how it goes, I am wondering what you would use for the alloy.

chris

LOL - I called them 'Lovejoy' couplers because I have Lovejoy labels on my existing ones :)

I've actually got 3 iron branded Lovejoys and a 'clamp-style' aluminim one, so I was tempted to just use 6082 to make mine.

I do take your point on time vs cost - I can get some fairly cheap iron couplers but I'd have to re-bore them to fit my shafts/motors and I'm a bit worried about doing it on my X-1 and doing it accurately. I do have a CNC'ed mill and a foot of 1" diameter 6082 rod to play with, so I think I'll at least have a go at one - I need 6 so it would be a significant cost saving but might be too tedious if it's going to take more than a couple of hours per coupler.

I'm also not too sure of the geometry of the couplers - it looks like the lugs are formed by slicing a round rod with a larger diameter arc, but I don't know how I'd measure the size of the arc. I suppose I could just buy some spiders and measure the space between the lugs.

Cheers.

In my post about My Mill Conversion (http://www.cnczone.com/forums/showthread?t.php=33770)

I ordered 4 sets of 1.750 diameter lovejoy couplers so i could do the exact same thing. I needed to bore the ID so I could get the lock nuts sunk into the coupler. It was interesting turning them down as the dust went everywhere. I also turned down the OD to remove some of the weight as I didn't relly need that big and strong of a coupler, but I had to get them so there was enough for me to do the ID work. If you would like I can try to get some better pics of them this weekend and post them for you, if you are interested. I bought the couplers from McMaster (http://www.mcmaster.com)

AC

I've seen people make both the Lovejoy/Oldham style as well as helical beam couplers:

http://www.thewarfields.com/cnccookbook/img/OthersProjects/StepperTable.jpg

http://www.thewarfields.com/cnccookbook/img/OthersProjects/FlexCoupler.jpg

In some cases, by making their own, they've integrated the design to require fewer parts which is cool. For example, the rotary table (by John Stevenson of the HSM board) has shopmade Oldham couplers and he has built one end to also act as the adaptor for the table.

I started out to make couplers for my mini-router. I bored a through hole and set screws, and on a lark, I tried it out as a solid coupler. They worked great, so I didn't bother with the conversion to helical beam.

http://www.thewarfields.com/cnccookbook/img/OtherTools/MiniRouter/P3063863.JPG

Best,

BW

Here is a coupler I made a while back using a bit of aluminum bar and some 3/32" rubber sheet. It can accommodate quite a lot of out of parallel but the shafts need to be fairly close axially.