Magnetic Tensioner (heads up for the Brits)

[peskywinnets]

Just gone & bought me one of these puppies...

B25) MT 100 TANAKA MAGNET TENSION UNIT NEW IN BOX on eBay (end time 29-Nov-10 09:44:19 GMT)

£32 delivered NEW (it seems the seller doesn't know much about them!)

I know cack all about it too, other than it'll handle 0.04mm-0.14mm wire (right in the ballpark for pickups) & will tension 12->100g, but at that price got to be worth having a dabble!

It's the lower spec of the two MT-100, ie it doesn't have 'BC' on the end for which the manafacturer says

"The BC models use a pneumatic cylinder to control the tension bar spring. This is a benefit when working on CNC winding machines where you want to de-tension the wire during terminal wrapping or pull the wire tight for reverse movements".

MT Tensioner

So, if that a deal breaker - beware.

One of its larger brothers is listed on Ebay Stateside ...

Tanac Magnetic Tension Unit - Wire / Coil Winder MT-300 on eBay (end time 02-Dec-10 02:00:17 GMT)

About £160 delivered for us Brits, so the the one I've linked to above seems a good deal

[NB70]

It seems some people are using the Tanac MT100 in pickup winding - http://music-electronics-forum.com/t1958/. The guy relisted some more & I just bought 2 for a total of £57 - thanks pesky!

[peskywinnets]

I'm glad you're 'in' ....we can figure it out together!

[Peter Naglitsch]

The seller doesn't seem to ship outside UK. If some brother would like to pick up one extra and forward it to me I would
1. Be a very happy man
2. of cause cover any shipping and extra costs that might appear.
If so, please PM me

Thanks for the tip Peskywinnets

[copperheadroads]

Yes is a shame , too bad they dont ship outside the UK or id be on this as well ..........group buy

[peskywinnets]

Got in touch with the seller - he just replied that sold the last 4 tonight (probably as a result of this thread - shame, on retrospect, I could have done with one more too!).

Bet he wishes he'd asked more now!

[peskywinnets]

It's all very well bagging a $600 item for $60, but when it arrives, you take it out the box & haven't a clue how to use it, well hmm....

Answer on a postcard please...

[Joe Gwinn]

It's all very well bagging a $600 item for $60, but when it arrives, you take it out the box & haven't a clue how to use it, well hmm....

Answer on a postcard please...

Tanac will most likely be able to provide directions.

What will also help a lot is to read the patent, US 4,526,329. Use PAT2PDF - Free PDF copies of patents: Download and print! to get a copy. Be aware that the drawings are close, but are not quite corrent or complete. That said, one can figure it out after a few reads, especially if one has the hardware in hand.

The postcard instruction is that the big black knob sets the tension while the knurled rod coming out of one edge of the box adjusts where the dancer arm (called the dynometer in the patent) comes to rest while in operation. The knurled rod that comes out of one face of the box is not in the patent, but most likely is discussed in a later patent. Search for patents assigned to Tanaka.

[NB70]

MT100 in use

You can see one in action in this video from Dean pickups:

Dean Pickups - Guitar Pickups completely assembled in the USA

[WindingMachines]

If any of you guys have any questions about our products then we're happy to help out

Stuart BLANCHARD
Tanac Europe Limited
Tanac Coil Winding Machine - Total Winding Technology

[Jimbosticks]

If any of you guys have any questions about our products then we're happy to help out
Stuart BLANCHARD
Tanac Europe Limited
]

Yeah, I have a question for you. What has Tanac done to correct the problems with the MT-100? After a couple years intermittent use, the tension they generate for a particular setting starts climbing. It also becomes unstable, and the wire is not played out smoothly - it becomes "lumpy". We know about the tension increases because we use a precision calibrated tension meter to check the tension at 3 month intervals. I've seen tensions climb from 60 grams to 90 grams at a setting of "8". This has happened to every machine we have used. And we've owned at least 10 of these machines. The Tanac facility in the USA had no answer for the problem. In fact, they don't even acknowledge it exists. Initially, they recommended an expensive re-calibration to us. We sent a number of units back for this. However, the "calibration" didn't solve the problem.

After years of working with the units, I isolated several contributors to the problem. I told Tanac USA and Tanac Japan about them. But they haven't even had the courtesy to respond. They apparently test all their tensioners in high speed, continuous operation with one specific wire gauge and one tension setting. Operated this way, they will not see a problem. However, change wire gauges, change settings, and let the machines sit idle for weekends, etc. and the tensions they generate WILL start climbing.

What happens? First you have to understand how the machine operates. Screwing the black tension control knob in, moves a magnet towards a metal plate. That plate is bolted to the tension pulley which carries the wire being tensioned. The closer the magnet is to the plate, the more magnetic attraction, and higher the tension. Behind the black knob is a brass cylinder which screws into fine threads in the plastic housing. As operators change the setting of this knob, it wears the plastic threads. This loosens the knob, and allows it to tilt downward a few thousandths under it's own weight. Now internally, the magnet, which is fixed to the brass cylinder, has also tipped closer to the metal backing plate of the tension pulley. Voila, tension increases.

There is another problem. The closer the magnet is to the plate, the more the plate itself becomes magnetized! If the bottom of the magnet is tipped towards the plate, and if the machine sits unused for several days or weeks, the plate develops a magnetic "pole". Run the machine a while, and then let the pulley sit at another position, and you develop a "pole" at another position. Those "poles" account for the growing "lumpiness" of the wire feed. I even figured out a way to see what was happening with the plate. You remove the metal plate (left hand threaded nut), and drop fine iron filings on the plate. The filings will group at the poles. If a machine sat unused at a high tension setting for weeks, more filings will accumulate at that particular spot on the plate.

One part of the solution is to demagnetize or replace the plate. It SHOULD be made from an iron with low magnetic retentivity. The other thing is to make the face plate of the housing out of something other than plastic. Something so the threads do not wear and allow the magnet to tip towards the tensioning plate.

These machines are almost $900. I suggested to Tanac that when they devise their fixes, they either issue kits to owners, or recall the machines for repairs. No response. In fact, no response to any of my comments, going on one year.

If anyone at Tanac can disprove my theory, and tell me what we're doing wrong, let him do it. However I have loads of accumulated data showing how tensions rise, as the machines age.

[Steve Conner]

If this is true it would explain why they can be picked up cheaply on Ebay. I'd expect all the second-hand ones to have lumpy feeds.

[the great waldo]

Hi Pesky

How did you get on with using the tensioner ?

Cheers

Andrew

[Joe Gwinn]

It SHOULD be made from an iron with low magnetic retentivity.

That plate must be made of a reasonable permanent magnet material, which by definition has high retentivity, which is another name for hysteresis. The Tanak Tensioner is based on a hysteresis brake.

It should be possible to smooth the lumps out by feeding some heavier wire through at high tension, or spinning the capstan with a drill while starting at heavy tension.

The other thing is to make the face plate of the housing out of something other than plastic. Something so the threads do not wear and allow the magnet to tip towards the tensioning plate.

They surely could use a better material. Can you tell what plastic it's made of?


Hmm. Maybe I can get a beater MT-100 for small dollars on eBay, for science.

[Jimbosticks]

That plate must be made of a reasonable permanent magnet material, which by definition has high retentivity, which is another name for hysteresis. The Tanak Tensioner is based on a hysteresis brake.

It should be possible to smooth the lumps out by feeding some heavier wire through at high tension, or spinning the capstan with a drill while starting at heavy tension.

They surely could use a better material. Can you tell what plastic it's made of?

Hmm. Maybe I can get a beater MT-100 for small dollars on eBay, for science.

When you turn the large black knob, that moves a permanent magnet inside the box towards or away from a ferrous metal plate which is connected to the backside of the external pulley. The ferrous plate is not normally magnetized. There is no reason for it to be. The positioning of the permanent magnet relative to the plate controls the tension.

Look, I don't know if the Tanac MT-100 classifies as a "hysteresis brake", but after 10 years of working with, and repairing them, I know what goes wrong. When the wire doesn't pull through the pulleys smoothly, the problem is spot magnetization of the plate. And the solution is to remove and demagnetize that plate. I've done that on at least 5 units, with great success. That is also why I think a plate made of soft iron or some other material with low retentivity would be advantageous. Actually, I'm not certain if it isn't made from iron already. I just know it gets magnetized. And that makes for "lumpy" wire feeding.

The units DO increase in tension as the plastic threads associated with the adjustment knob wear. These threads are cut into the plastic faceplate. When you replace the plastic faceplate the tension levels for a given setting return to the original values. That is because the magnet no longer tips inward towards the metal plate. I don't know what the cream colored plastic is. Maybe PVC or ABS. Personally, I think the faceplate should be made from aluminum, or the threads should be implemented with an insert made from brass. I have already designed such a faceplate, but do not have the machinery needed to cut the fine, large diameter thread.

I can't imagine how feeding some heavy wire through the wire pulleys, OUTSIDE the box, is going to fix what is going on INSIDE the box. Maybe you can explain that to me. Maybe continuous high speed operation will gradually demagnetize the metal plate. However, our machines go idle overnight, and over the weekend. And our operators have to change wire gauges and tension settings all the time. It wears the threads.