homemade flex couplers

you mean on ones like these:

Slitting saw. If you were to look at a section thru the cut you'd see a radius equal to that of the saw adjacent to "a" in your drawing.

Yes, exactly, and it's the slit that forms the clamp that I don't get-- it's deep and narrow, with a blind, square bottom.

How do they do that?

I made my own by turning and boring a cylinder (steel), then saw- cutting slits to create the flexible surfaces. They're surprisingly nice, and not that hard to make.

But, the setscrew thing mars the shafts, and doesn't grip as securely as a clamp. (I guess I could stuff a wad of brass in front of the screw-tips to prevent the marring, come to think of it).

James Arthur

Really? I just posted the opposite, that the cut's square-bottomed, but now that you say it I'm not so sure.

Would the hinge be flexible enough with a big arc of metal left at the bottom of that cut? I wouldn't think so, but if you're right it must be.

James Arthur

I've got a Helical brand beam coupling and a Huco Oldham coupling in front of me and both have a radiused bottom on the slit on the far side of the bore.

Without that radius at the bottom you would have a real nasty stress point at the corners of the slot.

Thanks! I just spent half an hour digging to see if I had one somewhere, but couldn't find a dang thing.

'Preciate that.

James Arthur

Yep, both that and how thin the "hinge" was troubled me--it didn't look strong enough.

I was thinking of forming the "pivot" area of the hinge (the part near 'a', the portion that bends as you tighten the clamp) by drilling, thus forming a rounded, stress-relief area. Like this (crappy drawing #2):

(view in Courier, or other fixed font)

/ / / / | a. ___ | _ / \ | / \_____| |_____ | | _____ _____ | \_/ | | | \___/ | \ \ \ \ / \_______________/

I still might do that.

Thanks a bunch to all, James Arthur

I just remembered a part I designed in the not too distant past that had that detail...

A Slitting saw should give you a fairly square bottom on the cut. They are spooky buggers to use though, a lot of teeth and a big unguarded area.

BobH

Indeed.

Say..if there are any questions..why not call Rocom..makers of Rocom Couplers

Ask for the Big Kahuna...tell him Gunner refered you.

Gunner

DISCLAIMER: The content does not reflect the thoughts or opinions of either my ISP, myself, my company or employer, my friends (if any,) my goldfish or my neighbour's mad dog; don't quote me on that; don't quote me on anything; all rights reserved; the post is distribution copyrighted to the extent that you may distribute the post and all its associated parts freely but you may not make a profit from it or include the post in commercial publications without written permission from the Prime Minister of Hutt Province; other copyright laws for specific posts apply wherever noted or not noted, either deliberately, negligently, or otherwise; posts are subject to change without notice; posts are slightly enlarged to show detail; any resemblance to actual persons, living or dead, is unintentional and purely coincidental; hand wash only, tumble dry on low heat; do not bend, fold, mutilate, or spindle; do not pass go; do not collect $200; your mileage may vary; no substitutions allowed; for a limited time only; the post is void where prohibited, taxed, or otherwise restricted; the post is provided "as is" without any warranties expressed or implied; user assumes full liabilities; not liable for damages due to use or misuse; an equal opportunity abuse employer; no shoes, no shirt; quantities are limited while supplies last; if defects are discovered, do not attempt to fix them yourself but return to an authorised post service centre; caveat emptor; read at your own risk; parental advisory - explicit words; text may contain material some readers may find objectionable, parental guidance is advised; not suitable for children; not suitable for adults; not for human consumption; keep away from sunlight, pets and small children; limit one-per-family; no money down; no purchase necessary; to approved purchasers only; facsimiles are acceptable in South Australia; you need not be present to read this post; some assembly required; batteries not included; action figures sold separately; no preservatives added; tools not included; safety goggles may be required during use; sealed for your protection, do not use if the safety seal is broken; call before you dig; for external use only; if a rash, redness, irritation or swelling develops, discontinue use; use only with proper ventilation; avoid extreme temperatures and store in a cool, dry place; keep away from open flames, naked flames and old flames; avoid inhaling fumes; avoid contact with mucous membranes; do not puncture, incinerate, or store above 60 degrees Centigrade; do not place near flammable or magnetic source; smoking the post may be hazardous to your health; the best safeguard, second only to abstinence, is the use of a good laugh; text used on the post is made from 100% recycled electrons and magnetic particles; no animals were used to test the hilarity of this post other than Synapse Syndrome; no salt, MSG, artificial colour or flavour added; may contain traces of replies to peanuts; if ingested, do not induce vomiting, if symptoms persist, consult your humourologist; post is ribbed for your pleasure; slippery when wet; must be 18 to read; possible penalties for early withdrawal; post offer valid only in participating newsgroups; slightly higher in South Australia; allow four to six weeks for delivery; damage from hurricane, lightning, tornado, tsunami, volcanic eruption, earthquake, flood, orgasm, misuse, self-abuse, neglect, unauthorised repair, damage from improper installation, broken antenna, marred cabinet, incorrect line voltage, missing or altered serial numbers, sonic boom vibrations, electromagnetic radiation from nuclear blasts or other Acts of God are not covered; incidents owing to aeroplane crash, ship sinking, motor vehicle accidents, leaky roof, broken glass, falling rocks, mud

detail...

Nice part. I wish my ASCII drawings looked that good!

-- Cheers, James Arthur

The problem's at the blind end of the cut, at the place I've labeled "a". There, using a slitting saw you get a radiused tab at the end of the cut, at the bottom.

Here's a drawing attempt: a section illustrating 1/2 of the clamp & showing the inside of the cut:

(view in Courier or other fixed font) _________________ / \ / \ / \ / \ / \ | ___ | | a. / \ b. | ^ | _______| |_________| ^ |__|_|_______________________________| | |_______ _________ | | | | | \___/ | | | \ / \ / \ / \ / \_________________/

. ------ . . ' ' . . . -- . . a. / _______/ /_________.| / /| | | b.|| | || | | || | || | | || | || | | || | |/\ | | || | \ \ | .' '| || | \ \___|/ |_________|/ | \/____________________/| / || / || left by saw's radius

So, if you can follow these drawings, you can see that a slitting saw's radius does not cut a square bottom, in that its radius leaves an arc-shaped tab uncut at the bottom, at the end of the cut.

I thought that'd be a problem, but apparently it's not.

Hope that's clear.

Cheers, James Arthur

Nice stuff they have there Gunner, but buying couplers would be faster, easier, better, and cheaper. That kinda defeats the whole purpose of making your own, doesn't it?

Grins, James Arthur

You guys actually buy em? Damn..and Ive been getting all mine free.

The OmniTurn CNC lathes that I service use 2 of them and I keep a handful in the truck all the time. Course..the owner is my friend....

Gunner

"Aren't cats Libertarian? They just want to be left alone. I think our dog is a Democrat, as he is always looking for a handout" Unknown Usnet Poster

Heh, heh, I'm pretty sure my dog is a liberal - he has no balls. Keyton

Or you are stuck in a lime grove in the middle of no where in Southern California with the flex coupler on an older Mercedes steering broke. My dad manufactured a new one out of an old tire they found. Always good to be handy. This was back in about 1960.

Indeed. Ive seen that done more than once, including big trucks. My mechanic rebuilt the flex on my old drill rig out on the line in the middle of sweet f*ck all in Montana, using a tire. It was still in there when I quit Western Geophysical a couple years and 5 states later.

Gunner

"Aren't cats Libertarian? They just want to be left alone. I think our dog is a Democrat, as he is always looking for a handout" Unknown Usnet Poster

Heh, heh, I'm pretty sure my dog is a liberal - he has no balls. Keyton