Timing 2 shafts

I have 2, 1" shafts that are about 1' apart with 4" tapered bushing type sprockets and #60 chain and an eccentric tensioner running about 100 rpm.
The shafts must be timed to within a couple of degrees. The last time I had to time them it took a couple of hours but they stayed in time well. Now, I'm going to have to take the unit apart to make improvements in another part. I'm thinking there might be a better device out there to time the sprocket onto one of the shafts with quick, easy and fine adjustment that will hold time perfectly. (I don't ask for much)...oh, and cheap too. I put a pix in the box:
http://www.metalworking.com/DropBox/ob-shaft_timing.jpg
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Tom Gardner wrote:

What do you presently change to time it?
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I loosen the taper bushings and move it a hair and re-tighten and hope.

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I'd suggest you look at these: http://www.packworld.com/articles/Products/331.html We use the Browning equivalents but all that I've used allow for 1 chain link adjustment..get it close and dial it in. R. Wink

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Tom The adjustable hubs that R Wink points to are what we use at the plant also to get that final few degrees we need on timing. lg no neat sig line
wrote:

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OOOOO XXXXXX (Hugs and kisses!...in a manly way of course))
wrote:

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On Sat, 31 Jul 2004 17:16:50 GMT, "Tom Gardner"
Oh, suuuuure. ;)
One old way was to use a pair of adjustable idlers to move the chain slack one way or another to time the fixed-pos. shafts. (At least that's one thing I think I remember about an old Multi 1250 printing press a buddy had.)

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Builders of competition engines have been timing cam shafts for years. The most common ways are stepped keys or vernia sprockets. Make you drive so that it uses plate sprockets and drill a number of possible mounting holes. A dividing head is good if you have one. Then choose the appropriate point to secure the sprockets. If the torque isn't too high, you can get away with slotted holes. I must admit I like Larry's idea of variable idler sprockets. Not come across that before.
John

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Ok..I gots to ask ya.....
machine looks like a 2 roller turks head to roll shaped wires. Not sure what it really does or why the timing would have to be perfect but I'd love to know.
As to your problem....assuming that you need to time things within about one chain pitch you should be able to do this by having double snubber rolls instead of just one (neglecting chain stretch over time). The chain over your driving and driven sprocket would be loose by about 2 to 4 chain links (hard to tell the size and clearance you have.) There would be another snubber roll on the opposite side of the chain loop similar to the existing one. BOTH snubbers would be on the same moveable mounting plate. What you have formed is a modified "X" shape of 4 sprockets with the chain loop over two and the snubbers as the other leg of the "X". By moving the snubber portion of the X along their axis (top one in farther as the bottom one goes out farther or the opposite) the timed roll will move by about 1 tooth. By putting the snubber axis on a screw adjuster you could technically get VERY accurate very quickly.
As usual, it's hard to describe in words but maybe someone will be better at it than me.
Note also that as each chain link hits the sprocket you will be a chordal speed variation in that sprocket. Your system appears to have 20 teeth which gives a speed variation of 1.23 % with each link. On smaller sprockets, this jerking speed variation can be felt and seen. I'm assuming that because you had success in the past the number is low enough to be negligable. I bring it up as it can introduce other weird effects like resonant whipping into the system and larger sprockets may be worth it if things are really critical here.
Koz
Tom Gardner wrote:

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The chain drives a shaft with a cam on the other end that hits an arm that cuts the flat wire that you see to 3". Each rotation makes a cut that must happen in about 2 degrees of rotation or I lose control of the cut wire or it isn't cut yet and jams the machine.

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A typical wire forming machine or 4 slide machine would be adjusted simply by moving the cams a bit (or shimming the slide that is driven by the cam where applicable.) I guess I misunderstood your system and how much variation you needed for that adjust.
Depending on the cam set-up you could have double set screws coming in sideways from both sides through the cam to a key fixed on the shaft. The keyslot in the cam is extra wide by the amount the cam may need to be rotated. Adjusting the screws would rotate the cam. Of course this is over simplified and you would need to modify the design so that you can transmit the energy without set screws failing.
On our cut-off machines, the cutter is set up to fly with the strip being cut also (about 1 inch) to prevent the kinds of jamming you are speaking of. We cut off about 10,000 formed wires or strips a day. Of course we generally cut a little longer so there would be more time between cuts. Our material is moving through the machines at about 100 fpm.
We've never had problems getting the cam coarse adjusted. There are lots of systems that can do the fine adjustments from there. I guess I'm still a little lost.
Koz
Tom Gardner wrote:

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wrote:
||I have 2, 1" shafts that are about 1' apart with 4" tapered bushing type ||sprockets and #60 chain and an eccentric tensioner running about 100 rpm. ||The shafts must be timed to within a couple of degrees. The last time I had ||to time them it took a couple of hours but they stayed in time well. Now, ||I'm going to have to take the unit apart to make improvements in another ||part. I'm thinking there might be a better device out there to time the ||sprocket onto one of the shafts with quick, easy and fine adjustment that ||will hold time perfectly. (I don't ask for much)...oh, and cheap too.
Quick Easy Fine Adjustment Hold time perfectly.
Pick 3 Texas Parts Guy
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So far, my best idea is to mill the shaft and broach the bushing and make a bunch of off-set keys.
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had
If you won't be replacing anything to do with timing, can't you match mark every single piece, including the chain to the sprocket? This way, everything will be exactly as it was before coming apart. When I say match mark I mean with a scribe, not with a sharpie.
Shawn
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I agree, but the chain will stretch and must be adjusted eventually. (I only have crayons for marking)
"Shawn" <shawn_75ATcomcastDOTnet> wrote in message

rpm.
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Tom Several companies make an adjustable cam gear for soem of the earlier VW engines. You could take that principle to make up a set of sprokets for you machine or maybe adapt these gears and replace the chain with a toothed belt. That would reduce the chain stretch. Here's a pic of the gear
http://image.inkfrog.com/pix/PerformanceCafe/155.jpg
Tom Gardner wrote:

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Oh, you're looking for a long term solution. First, buy a scribe. Second, ditch the eccentric tensioner for two opposed rigid, screw adjust tensioners and add a few inches to the chain length. This way, by balancing the two tensioners, you could adjust the machine while running. Pulling a little more chain onto one of the tensioners would change the relationship of the two shafts.
Shawn

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(some) motorcycles have a steel chain that runs from the crank to the gearbox which is designed to deal with wear - each tooth profile is composed of an angled part of two plates. When the pins and sprockets wear, the teeth become larger. Maybe you could use such a chain...
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Gates Timing belt. Make the pulleys with radius slots, so you can fine tune.
--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
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What's that Lassie? You say that "Tom Gardner"
mine and will die if we don't mount a rescue by Fri, 30 Jul 2004 18:31:20 GMT:

Could you use two eccentric tensioners one on each side. Slacken one, and take up the other to shift the timing a few degrees.
--

Dan

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