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:
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Reply to
Tom Gardner
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What do you presently change to time it?
Reply to
Jim Stewart
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:
Reply to
Koz
||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
Reply to
Rex B
I loosen the taper bushings and move it a hair and re-tighten and hope.
Reply to
Tom Gardner
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.
Reply to
Tom Gardner
So far, my best idea is to mill the shaft and broach the bushing and make a bunch of off-set keys.
Reply to
Tom Gardner
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:
Reply to
Koz
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
Reply to
Shawn
I agree, but the chain will stretch and must be adjusted eventually. (I only have crayons for marking)
Reply to
Tom Gardner
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.> I agree, but the chain will stretch and must be adjusted eventually. (I
Reply to
Machineman
"Tom Gardner" wrote in news:YtwOc.2338$uC7.245 @newssvr19.news.prodigy.com:
Gates Timing belt. Make the pulleys with radius slots, so you can fine tune.
Reply to
Anthony
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
Reply to
Shawn
What's that Lassie? You say that "Tom Gardner" fell down the old rec.crafts.metalworking 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.
Reply to
dan
I'd suggest you look at these:
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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
Reply to
R. Wink
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
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We use the Browning equivalents but all that I've used allow for 1 chain link adjustment..get it close and dial it in.
Reply to
larry g
Shaft sync is a big deal in the printing industry, so there are good solutions. Shaft encoders, variable phase motors and FDDI loops are at the high end.
There is a specific gearing tool to let the press operator manually adjust shaft phasing while the press is running. Works great.
You can use simple toothed gears and inductive pickups on a dual trace oscope. But how to have dynamic variance?
Look at the variable phasing mechanism on the current GM Vortec 4.6 in-line engine's exhaust cam. That would work.
More basically, you gear two shafts together, but use a spiral cut gear pinned to one shaft, but splined to the second shaft. Something holds gear #2 in a position along the shaft. If you move the gear along the shaft, it has to turn the shaft, adding a phase variance between the shafts.
Reply to
frank
(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...
Reply to
jtaylor
OOOOO XXXXXX (Hugs and kisses!...in a manly way of course))
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We use the Browning equivalents but all that I've used allow for 1 chain link adjustment..get it close and dial it in.
Reply to
Tom Gardner
On Sat, 31 Jul 2004 17:16:50 GMT, "Tom Gardner" calmly ranted:
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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Reply to
Larry Jaques

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