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Post by svart on Mar 13, 2017 14:17:36 GMT -6
So on the new tape machine the pinch roller turned out to be hard as a rock and splitting. Also, once I started cleaning the oxide off the rubber, it started turning to goo immediately!
Anyway, rebuilt rollers are like 300+$, which is honestly ridiculous.
I haven't taken any pictures yet, but I did a few tests of different things I've done to remedy the situation.
1. Machined a new hub and pressed in precision bearings. The shaft is 10mm OD. The hub is 55mm long, 50mm OD. I found some polyurethane tubing that was roughly 45mm ID with about 52mm OD when it was stretched over the hub. The hub has a runout of around 0.01mm, but the OD of the urethane is more like 1mm runout. It's shore 65A, so it's pliant but not overly soft. It has a very slight dimple from the capstan shaft, which means it has good contact and pressure. The tension arm is spring loaded, so the runout simply causes the arm to sway slightly as the roller turns. I tried some tests but could not find a good way to lathe the urethane. The elastic nature of it seems to cause cupping while machining.
2. Stripped the old rubber off the original hub and replaced with some flexible PVC tubing, also Shore 65A. This one has an OD runout of closer to 0.1mm. It rolls much nicer, although it doesn't have quite the "grippyness" that the urethane does, but it does take considerable drag to cause slippage on the capstan shaft, so I don't think it's going to be much of a problem.
Either way, it's about 20$ in materials for the urethane tube, bearings and raw aluminum rod. It was about 3$ for the PVC tube.
If the PVC tube works, then I have a super cheap option for folks to fix their dried up/gooey pinch rollers.
I'll take some pictures while I test the tape feeding tonight.
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Post by johneppstein on Mar 13, 2017 14:28:14 GMT -6
So on the new tape machine the pinch roller turned out to be hard as a rock and splitting. Also, once I started cleaning the oxide off the rubber, it started turning to goo immediately! Anyway, rebuilt rollers are like 300+$, which is honestly ridiculous. I haven't taken any pictures yet, but I did a few tests of different things I've done to remedy the situation. 1. Machined a new hub and pressed in precision bearings. The shaft is 10mm OD. The hub is 55mm long, 50mm OD. I found some polyurethane tubing that was roughly 45mm ID with about 52mm OD when it was stretched over the hub. The hub has a runout of around 0.01mm, but the OD of the urethane is more like 1mm runout. It's shore 65A, so it's pliant but not overly soft. It has a very slight dimple from the capstan shaft, which means it has good contact and pressure. The tension arm is spring loaded, so the runout simply causes the arm to sway slightly as the roller turns. I tried some tests but could not find a good way to lathe the urethane. The elastic nature of it seems to cause cupping while machining. 2. Stripped the old rubber off the original hub and replaced with some flexible PVC tubing, also Shore 65A. This one has an OD runout of closer to 0.1mm. It rolls much nicer, although it doesn't have quite the "grippyness" that the urethane does, but it does take considerable drag to cause slippage on the capstan shaft, so I don't think it's going to be much of a problem. Either way, it's about 20$ in materials for the urethane tube, bearings and raw aluminum rod. It was about 3$ for the PVC tube. If the PVC tube works, then I have a super cheap option for folks to fix their dried up/gooey pinch rollers. I'll take some pictures while I test the tape feeding tonight. What's flutter like? BTW, what did you attempt to clean the roller with - you should NEVER use alcohol - it eats the rubber. The advice in the old days was to use dish detergent in warm water, but Precision Motor Works sells a head and roller cleaner that is just amazing and won't eat your rubber. www.precisionmotorworks.com/shop/contents/en-us/d14.html |
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Post by svart on Mar 13, 2017 15:04:21 GMT -6
So on the new tape machine the pinch roller turned out to be hard as a rock and splitting. Also, once I started cleaning the oxide off the rubber, it started turning to goo immediately! Anyway, rebuilt rollers are like 300+$, which is honestly ridiculous. I haven't taken any pictures yet, but I did a few tests of different things I've done to remedy the situation. 1. Machined a new hub and pressed in precision bearings. The shaft is 10mm OD. The hub is 55mm long, 50mm OD. I found some polyurethane tubing that was roughly 45mm ID with about 52mm OD when it was stretched over the hub. The hub has a runout of around 0.01mm, but the OD of the urethane is more like 1mm runout. It's shore 65A, so it's pliant but not overly soft. It has a very slight dimple from the capstan shaft, which means it has good contact and pressure. The tension arm is spring loaded, so the runout simply causes the arm to sway slightly as the roller turns. I tried some tests but could not find a good way to lathe the urethane. The elastic nature of it seems to cause cupping while machining. 2. Stripped the old rubber off the original hub and replaced with some flexible PVC tubing, also Shore 65A. This one has an OD runout of closer to 0.1mm. It rolls much nicer, although it doesn't have quite the "grippyness" that the urethane does, but it does take considerable drag to cause slippage on the capstan shaft, so I don't think it's going to be much of a problem. Either way, it's about 20$ in materials for the urethane tube, bearings and raw aluminum rod. It was about 3$ for the PVC tube. If the PVC tube works, then I have a super cheap option for folks to fix their dried up/gooey pinch rollers. I'll take some pictures while I test the tape feeding tonight. What's flutter like? BTW, what did you attempt to clean the roller with - you should NEVER use alcohol - it eats the rubber. The advice in the old days was to use dish detergent in warm water, but Precision Motor Works sells a head and roller cleaner that is just amazing and won't eat your rubber. www.precisionmotorworks.com/shop/contents/en-us/d14.htmlDon't know the flutter yet, I haven't run any tape on it yet. I'll know shortly! I used soapy water as you also suggested, but the rubber from this era is known for this. i think the tape oxide that was on it was keeping the rubber from deteriorating and as soon as it got fresh oxygen it started to goo. it was already too hard to function, so it's not like I ruined it. The worst case would be sending the hub to be re-built and spending the money. Best case is that it works. I'm cautiously optimistic. |
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Post by johneppstein on Mar 13, 2017 16:05:57 GMT -6
What's flutter like? BTW, what did you attempt to clean the roller with - you should NEVER use alcohol - it eats the rubber. The advice in the old days was to use dish detergent in warm water, but Precision Motor Works sells a head and roller cleaner that is just amazing and won't eat your rubber. www.precisionmotorworks.com/shop/contents/en-us/d14.htmlDon't know the flutter yet, I haven't run any tape on it yet. I'll know shortly! I used soapy water as you also suggested, but the rubber from this era is known for this. i think the tape oxide that was on it was keeping the rubber from deteriorating and as soon as it got fresh oxygen it started to goo. it was already too hard to function, so it's not like I ruined it. The worst case would be sending the hub to be re-built and spending the money. Best case is that it works. I'm cautiously optimistic.Well, keep us posted. I have a fairly new roller on my Studer, but it's good to know these things. BTW, I can't recommend that PRW cleaner highly enough. It's a tad on the expensive side but it takes very little so it lasts a long time as long as you seal the bottle tightly. Refrigeration helps, too. When we first got some we cleaned the heads with 97% alcohol like we had been using until they were clean and shiny with no visible gunk at all. Then we cleaned them again with the PRW styff and the swabs came off with a shocking amount of black schmootz. |
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Post by donr on Mar 13, 2017 22:04:13 GMT -6
I remember from the day (mid 70's) having a TEAC mantainance kit with a bottle of pinch roller cleaner that smelled kinda stanky.
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Post by Deleted on Mar 14, 2017 3:00:17 GMT -6
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Post by svart on Mar 17, 2017 7:09:59 GMT -6
Don't know the flutter yet, I haven't run any tape on it yet. I'll know shortly! I used soapy water as you also suggested, but the rubber from this era is known for this. i think the tape oxide that was on it was keeping the rubber from deteriorating and as soon as it got fresh oxygen it started to goo. it was already too hard to function, so it's not like I ruined it. The worst case would be sending the hub to be re-built and spending the money. Best case is that it works. I'm cautiously optimistic.Well, keep us posted. I have a fairly new roller on my Studer, but it's good to know these things. BTW, I can't recommend that PRW cleaner highly enough. It's a tad on the expensive side but it takes very little so it lasts a long time as long as you seal the bottle tightly. Refrigeration helps, too. When we first got some we cleaned the heads with 97% alcohol like we had been using until they were clean and shiny with no visible gunk at all. Then we cleaned them again with the PRW styff and the swabs came off with a shocking amount of black schmootz. So I finally ran audio in/out of the unit. Sounded pretty good! there was indeed a little wow, so I worked on the rollers again. The one I machined would not work, the run-out of the rubber tube is still too high. I worked on the original roller that I had placed the PVC tubing on since it was much, much better. I didn't have a lathe bit of the right geometry to cut the PVC cleanly, so I thought of things to do... So I froze the roller to make the plastic hard, and easily machinable. I got the WOW down to the point where you can't hear it if you're not really listening. I'll try to face off the plastic better tonight or this weekend, and then attempt the same on the polyurethane roller and see if freezing it works as well. |
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Post by svart on Mar 21, 2017 8:35:00 GMT -6
I attempted facing the plastic a little more. The PVC roller was no sweat, it probably has a runout of less than 0.5mm. It's barely visible to the eye. My dial gauge is in storage somewhere so I don't have it handy to measure. The polyurethane roller didn't fare so well. I couldn't freeze it enough to make the urethane hard enough to machine freely. I did try cold spray, which worked if I kept the spray going while machining, but the second I let off the spray, the urethane would start to skip again.
I think I'll freeze the PVC roller again and do another pass with fine sandpaper to ensure it's nice and smooth and leave it at that.
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