Upgrade for users of 1/2" mylar belt


This thread will be of interest to Galibier, Redpoint and Teres belt drive TT owners, or anyone using or thinking of using a drive belt made from 1/2" mylar. The belt material of choice on these tables for several years has been the silver holographic mylar streamers from sources linked on the Teres and Galibier websites. This outperforms everything else we've tried but like anything it's not perfect - and we've now found something better.

One of the silver holographic mylar's assets can also become a liability. That metallic layer, when new, gives the belt exceptional "grip" on the platter and motor capstan. Minimal slippage on transients is one reason the material works so well. Unfortunately, that layer can wear over time, leaving a silvery gray residue and allowing performance to deteriorate. The only solution has been a good cleaning and a new belt. No big deal, but if there was a better or more stable belt Paul and I wanted to find it.

I'll spare you a recounting of our many experiments and jump to the good news: thanks to (yet another) brainstorm by my resident genius/partner, we've developed a belt that both performs better and lasts longer. I've held off posting until we were sure, but after 4 months of steady use Paul’s idea is still working perfectly. The only negative is that making this new belt takes an hour or more of work spread over two days, but to us it's worth the effort.

HOW TO MAKE ONE

1. Cut a length of the silver holographic mylar tape sufficient for your TT, plus 3-4" extra.

2. Remove the silver metallic coating off the backside of the mylar. Paul used an acid etching cream popular with stained glass hobbyists to dissolve the metal - safe, quick and easy (use skin and eye protection).

3. Rinse thoroughly under running water, inspect to make sure you got all the silver off, wipe and hang to dry overnight.

4. Splice as normal to make a TT belt, making sure you tape on the OUTSIDE (which will be smoother than the now bare inside).

5. As always, the best splicing technique is to overlap the ends and cut on a 30-40 degree angle. Apply 1” video splicing tape (*not* tabs) across the belt at the *same* angle and trim away the excess.


WHY IT PERFORMS BETTER

Unlike any plain mylar ribbon you could easily buy, the silver holographic streamer has an ultra fine texture embossed on the back side of the *mylar* during manufacturing (*before* the metallic backing is applied). Once the silver layer is applied you can't see this texture, but that's what diffracts light like a million tiny prisms to produce the shimmery rainbow effect. Stripping the metal backing away exposes this texture, which becomes the contact surface of your new belt.

Paul realized this texture must exist and then hypothesized that using it for the working side of a TT belt might provide more “grip” on the platter rim and motor capstan than either plain mylar (which is extremely smooth) or the metallic backing. He was right. This belt produces more lifelike dynamics, both macro- and micro-, than even a brand new silver holographic belt - which heretofore was the best.

WHY IT LASTS LONGER

Removing the metallic backing exposes bare mylar, which is much sturdier than that fine layer of metal. Under normal use and assuming no accidents, one of these belts should last many, many months, perhaps years, while delivering consistent performance. Ours is going into its fifth month with few visible and no audible signs of wear.

Different motor capstan materials might interact with this belt differently, but I urge anyone with a compatible table to give this a try. Like all our favorite little tweaks, we'd find it hard to go back.

A FEW TIPS

1. Clean any silver/grey residue from your old belt off the motor capstan and platter before mounting the new belt.

2. As many of us have learned, the more inelastic the belt, the more critical motor leveling becomes. That is truer than ever with this new belt. Getting the motor set just right is touchy. Take care that your new belt is riding level in the center of the capstan before you start to play. You don't want it sliding up or down and mangling itself.

3. Motor distancing is also more critical than ever. Since this belt will not slip *or* stretch, tension must be perfect. The right amount is just shy of the tension that would tilt the motor off its feet.

4. Depending on your climate, the belt can build up static potential during use. Not enough to spark, but more than enough to attract airborne dust. I dust the belt's inside with my CF brush after each side before stopping the platter.

5. With this or any belt, always start your platter spinning with a helping push. Just pressing the motor's ON button creates lots of belt-wearing friction as the rapidly spinning motor tries to drag that heavy platter up to speed.

It all sounds like a pain, and it is! But the sonic and longevity results are worth the effort.

Cheers,
Doug
dougdeacon

Showing 10 responses by frank_sm

Thanks Doug, I made a couple of belts yesterday and used the 1/2" splicing tape since that's what I ordered. I think it will hold just fine. It's a lot stronger than the silver splices I was using. Thanks for your continued support!
I've always had problems with the belt "stretching" at the spliced area so that the adhesive area of the splice becomes exposed after only a few hours of playing. This exposed area becomes larger as time goes by and the larger it gets, the more noticable the sound as it passes by the pulley.
Is there a know splice material that outperforms all available? That is my main gripe with mylar tape, the stretching.
I haven't yet tried the method Doug outlined in this thread but I'd like to, only if I can find a solution to the stretching of the belt at the splice point. Any ideas?
I'm using the silver tabs. Can you offer a link to the splicing tape you recommend?
I'm also using Silver holographic tape. Is there a better type of tape than this? I'm not that keen on the color silver anyway. Thanks for your help Doug!
I just ordered the etching creme. I reread the thread and found it, many thanks.
Regarding the splicing tape, Is there any splicing tape available that matches the colour of the tape?
Doug, Is it 1" wide splicing tape you use? I ordered 1/2" wide splicing tape and it's not quite as wide as the Silver tape. I think I ordered the wrong tape now.
http://usrecordingmedia-store.stores.yahoo.net/1inch.html
Don't be too quick to replace the belt. It's a lot colder now, being winter, and thermal expansion will have an affect on your belt. I know that since I've been using a tape drive for the past 3 years this is exactly what happens when the temperature changes, the belt creeps up or down on the pulley and you have to re-tension it.
I machined a leveling base (has 3 adjustable leveling feet) for my motor pod to sit on and this makes it easy to dial in belt alignment and also helps isolate it.
Regarding the cogging issues with the Hurst AC motors, the 300RPM motors have 24 poles, twice as many as the 600RPM motors so cogging is much more moticable with the 600RPM motors. I have at least 3 Hurst AC motors in the shop right now. I only use them as backups.
Doug, I don't see the frosted colour splicing tape on the website you mentioned.
I only use straight profile non-convex/concave pulleys on my tape drive table. Anything else I tried didn't work anyway. I assumed that's what Teres used.
Yes, it is a PITA to get the belt running properly but once set up, it's fine. You really need a leveling mechanism (which I have) under the motor to make it easier to true up the tape rotation.
Hi Doug, Thanks Jfd01 for the link. I'd like to make one of these belts. I haven't had the time to even locate where to purchase the "etching creme"
I'd like to see if you can clarify something for me. I've read over your initial instruction and want to make sure I understand the process.
The stripping is actually performed on the side of the belt that would normally be the NON-contact side, the shiny silver side. Then after stripping this surface it becomes the contact surface with the platter, is this correct?
Also, is there a known source and name for the etching creme? Thanks again!