Need ideas, measuring cable lengths

JimGlass · Jun 10, 2006

I have an opportunity to design a small machine for a customer. A first for my home machine shop.

We need a way to measure different lengths of 1/16" dia. cable from a spool. One job may require a thousand lengths at 12" and the next job 30" lengths of cable. We need a simple way for the machine operator to set cable lengths by moving stops or entering values. The lengths may vary by +/- 1/4" or more. Speed and cutting the cable is not an issue either. This machine will have a programmable controller.

Looking for something less expensive than a touch screen and servo motor. I first thought of using a bar type feeder with adjustable stops and multiple feeds for longer lengths. But the cable will most likely buckle when pushing the cable while feeding.

Gota be an easy way of doing this?

Appreciate some ideas,
Jim

JimGlass · Jun 10, 2006

I have an opportunity to design a small machine for a customer. A first for my home machine shop.

We need a way to measure different lengths of 1/16" dia. cable from a spool. One job may require a thousand lengths at 12" and the next job 30" lengths of cable. We need a simple way for the machine operator to set cable lengths by moving stops or entering values. The lengths may vary by +/- 1/4" or more. Speed and cutting the cable is not an issue either. This machine will have a programmable controller.

Looking for something less expensive than a touch screen and servo motor. I first thought of using a bar type feeder with adjustable stops and multiple feeds for longer lengths. But the cable will most likely buckle when pushing the cable while feeding.

Gota be an easy way of doing this?

Appreciate some ideas,
Jim

precisionworks · Jun 10, 2006

Most commercial units look like this photo: http://www.olympicinstruments.com/images/oly1700_in_use.gif

There's an inlet guide, a U-groove for the cable, a pressure roller that turns a counter, and an exit guide.

precisionworks · Jun 10, 2006

Most commercial units look like this photo: http://www.olympicinstruments.com/images/oly1700_in_use.gif

There's an inlet guide, a U-groove for the cable, a pressure roller that turns a counter, and an exit guide.

mjk · Jun 10, 2006

Unless this is being done for your own curiousity, why not find one already complete.
There are wire and tubing machines already on the market that do this.
Find one on Ebay, clean it up and resell it to your customer.
check out Cable Cutter

mjk · Jun 10, 2006

Unless this is being done for your own curiousity, why not find one already complete.
There are wire and tubing machines already on the market that do this.
Find one on Ebay, clean it up and resell it to your customer.
check out Cable Cutter

slipfit · Jun 10, 2006

Im seeing the cable being pulled out to length by a trailing clamp as leading clamp pulls the cutoff to next operation. The cutoff would happen just in front of the trailing clamp.

Dave

slipfit · Jun 10, 2006

Im seeing the cable being pulled out to length by a trailing clamp as leading clamp pulls the cutoff to next operation. The cutoff would happen just in front of the trailing clamp.

Dave

Ronnie · Jun 10, 2006

Jim

Could you use a star wheel and a prox switch? Then count the pauses with your PLC. This would be cheaper than an encoder or servo.

Also, I was just thinking, could you drill a series of small thru holes around the circumference of a small piece of pipe or some other small cylindrical object. Then use a smaller prox than the holes and count the pauses.

The drive could be a simple small electric motor with gear reduction box equipped with one concave friction wheel one flat.

Ronnie · Jun 10, 2006

Jim

Could you use a star wheel and a prox switch? Then count the pauses with your PLC. This would be cheaper than an encoder or servo.

Also, I was just thinking, could you drill a series of small thru holes around the circumference of a small piece of pipe or some other small cylindrical object. Then use a smaller prox than the holes and count the pauses.

The drive could be a simple small electric motor with gear reduction box equipped with one concave friction wheel one flat.

5thwheel · Jun 10, 2006

Run the cable over a roller of a given diameter attached to a rev. counter.

Bill

5thwheel · Jun 10, 2006

Run the cable over a roller of a given diameter attached to a rev. counter.

Bill

chuckey · Jun 10, 2006

Put on a false beard and big hat and go into a shop that sells material for curtains. You should find a machine that handles the loose rolls of materials and measures the amount being pulled through it. Go away and copy it?
If this cable is fairly stiff, then if it is pushed along a track then the distance between the cutters and a sensitive micro switch could be the required length, no counters,slippage of rubber pulleys etc easy to calibrate, sound simple to me.
Frank

chuckey · Jun 10, 2006

Put on a false beard and big hat and go into a shop that sells material for curtains. You should find a machine that handles the loose rolls of materials and measures the amount being pulled through it. Go away and copy it?
If this cable is fairly stiff, then if it is pushed along a track then the distance between the cutters and a sensitive micro switch could be the required length, no counters,slippage of rubber pulleys etc easy to calibrate, sound simple to me.
Frank

matt_isserstedt · Jun 10, 2006

One tactic is to use an air cylinder (clamp cable end and pull out)

With a magnetic piston and an external reed switch a solenoid valve can be turned off. The reed switch would be moved and tweaked for a new position to give a new length.

With a flow control (slow speed), this should be reasonably precise.

You'd have to have some assurance of max length, this couldn't go on forever, unless you gang up cylinders back to back.

Controls and hardware wise this is rather simple (could almost do this with true hardwired relay logic and forego the expense of a PLC). But a lot of compressed air would go down the drain operating it.

matt_isserstedt · Jun 10, 2006

One tactic is to use an air cylinder (clamp cable end and pull out)

With a magnetic piston and an external reed switch a solenoid valve can be turned off. The reed switch would be moved and tweaked for a new position to give a new length.

With a flow control (slow speed), this should be reasonably precise.

You'd have to have some assurance of max length, this couldn't go on forever, unless you gang up cylinders back to back.

Controls and hardware wise this is rather simple (could almost do this with true hardwired relay logic and forego the expense of a PLC). But a lot of compressed air would go down the drain operating it.

matt_isserstedt · Jun 10, 2006

Another version of above would be to use a twin-counterweighted roller chain that ran flat along a table for some length, then vertically downward on both ends. Ideally, the chain would be a long continuous loop with idlers and a tensioner sprocket, because this eliminates any issues with "pushing" the chain.

Use a 3ph motor and a wormgear reduction to a drive sprocket (could be under the table on a continuous looped chain)

You'd have to design a setup that has moveable stops that can attach to the chain for "home" and "cut".

But this would avoid the continual expense of running a compressor as above, and also involve very simple controls.

I still like the idea of a pneumatic gripper but a small-bore Bimba cylinder with a short stroke takes a lot less air than a long-bore "feed" cylinder.

matt_isserstedt · Jun 10, 2006

Another version of above would be to use a twin-counterweighted roller chain that ran flat along a table for some length, then vertically downward on both ends. Ideally, the chain would be a long continuous loop with idlers and a tensioner sprocket, because this eliminates any issues with "pushing" the chain.

Use a 3ph motor and a wormgear reduction to a drive sprocket (could be under the table on a continuous looped chain)

You'd have to design a setup that has moveable stops that can attach to the chain for "home" and "cut".

But this would avoid the continual expense of running a compressor as above, and also involve very simple controls.

I still like the idea of a pneumatic gripper but a small-bore Bimba cylinder with a short stroke takes a lot less air than a long-bore "feed" cylinder.

JimGlass · Jun 11, 2006

Decided to post pic of machine. The linear slide to the right was supposed to be the feed system like a bar feeder. Adjustable with stops and a selector switch for multiple feeds. It dawned on me the small cable cannot be fed by pushing it. The apparatus to the left is the cut-off system. The cable will be burned to cut using electric current. Before cutting, the cable will be rotated and pulled at the same time for a clean separation. An air actuated collet system will grip the cable.

The slide bar feeder is what needs to be replaced with better feed and measuring system.
The cable is not shown but is fed from right to left. The cable must be fed into the far left collet closer for the next cycle.

It all runs on air. A rotary actuator does the turning, a linear slide does the pulling, pancake air cylinders close the collets.

Last night I remembered working with a thumb wheel switch years ago. In one of the Allen-Bradely Reference manuals they show how to convert binary codes from the the thumb wheel switch to integer values. I think the integer values can be moved into a counter recieving counts from some kind of encoder. The cable could then be driven by a rubber wheel and DC gear motor. Primative but simple and effective.
I'll try it sometime soon.
Jim

JimGlass · Jun 11, 2006

Decided to post pic of machine. The linear slide to the right was supposed to be the feed system like a bar feeder. Adjustable with stops and a selector switch for multiple feeds. It dawned on me the small cable cannot be fed by pushing it. The apparatus to the left is the cut-off system. The cable will be burned to cut using electric current. Before cutting, the cable will be rotated and pulled at the same time for a clean separation. An air actuated collet system will grip the cable.

The slide bar feeder is what needs to be replaced with better feed and measuring system.
The cable is not shown but is fed from right to left. The cable must be fed into the far left collet closer for the next cycle.

It all runs on air. A rotary actuator does the turning, a linear slide does the pulling, pancake air cylinders close the collets.

Last night I remembered working with a thumb wheel switch years ago. In one of the Allen-Bradely Reference manuals they show how to convert binary codes from the the thumb wheel switch to integer values. I think the integer values can be moved into a counter recieving counts from some kind of encoder. The cable could then be driven by a rubber wheel and DC gear motor. Primative but simple and effective.
I'll try it sometime soon.
Jim

Need ideas, measuring cable lengths

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