I got an email from Sean Henderson last night referencing spec sheet for the maxon motor. according to the spec sheet the maximum dynamic axial load for the motor is 1.9 newtons which translates to 170 grams of mass. With a pulley that only weights 80 grams that should be a non issue. As I recall the motor we are using uses sleeves and not ball bearings this limits that radial load to 5.5 newtons or 550 grams 5.5 mm from the flange. Even taking the large distance to the belt contact point, I can't imagine achieving 550 grams of force.
Patriz, I'm not sure what would have caused your motor to fail. None of these weights comes even close to the speced uses of the motor. Also a max force of 80 newtons for press fitting is specified. I'm not sure how you would have done that. Thats 8.1 kg!! Yikes. I'm not sure where you would hold on to do that.
I don't know for sure, but I don't think the weight should matter to the pulleys. On that note, if another GB is going to happen, I would suggest either aluminum or Delrin.
Dave
Patriz, I'm not sure what would have caused your motor to fail. None of these weights comes even close to the speced uses of the motor. Also a max force of 80 newtons for press fitting is specified. I'm not sure how you would have done that. Thats 8.1 kg!! Yikes. I'm not sure where you would hold on to do that.
I don't know for sure, but I don't think the weight should matter to the pulleys. On that note, if another GB is going to happen, I would suggest either aluminum or Delrin.
Dave
I will take 1 motor and 1 PCB. I have access to CNC machining equipment that I can do weekend runs on. So if there are designs for pulleys and spindles that people would agree on I would be able to make them but I don't have time for custom one of parts.
Just saw the order was finished :-( so if there are any left overs let me know, maybe someone wants to back out 🙂
Just saw the order was finished :-( so if there are any left overs let me know, maybe someone wants to back out 🙂
Well, officially the group buy is closed, but I continue to receive request. There was the Pulley question that was a real problem for us.
If Greg Nuspel can save us with a custom pulley, I'll try to get my motor order modify to get 50 motors, Then we can order 50 pulleys. I already ordered 50 PCB, so the kits will be complete.
Greg. If you can make the pulley, and the members that already pay me for their pulleys agree, I'll be glad to transfer you the money I have already for the pulleys.
DaveM, I'll send all the info I have on the pulley to Greg.
In the meantime, here your original design ACAD drawing with all the quotes. As you mentionned that the crown curve was maybe too much, I cutted it in half on this drawing. Please comment.
If it seems like a sound design, we can go ahead with Greg and get some estimate. I think we can hit for at least 50 pulleys.
If Greg Nuspel can save us with a custom pulley, I'll try to get my motor order modify to get 50 motors, Then we can order 50 pulleys. I already ordered 50 PCB, so the kits will be complete.
Greg. If you can make the pulley, and the members that already pay me for their pulleys agree, I'll be glad to transfer you the money I have already for the pulleys.
DaveM, I'll send all the info I have on the pulley to Greg.
In the meantime, here your original design ACAD drawing with all the quotes. As you mentionned that the crown curve was maybe too much, I cutted it in half on this drawing. Please comment.
If it seems like a sound design, we can go ahead with Greg and get some estimate. I think we can hit for at least 50 pulleys.
Attachments
Final price for the PCB will be 30$. It includes the gold option, shipping and taxes to me. I'll add the small 5$ correction in the last cost correction at the time of shipping.
Bye....
Bye....
Bear in mind that for some of us the Teres is still the better option, so not everyone will want the custom pulley. The Teres certainly works out better for my applications.
Toaster said:
agreed. I will only be interested if the new pully supports a string option and is (easily) removable.
I want 33 & 45 rpm, and have decided that I want a tape drive, so will happily switch from one Teres plus one Bix to one (only) custom pulley; but will also honour the commitment I've already made if making the change is a hassle for algar_emi.
Regards.
Aengus
Regards.
Aengus
Hi. On the pulley business, I suggest we wait and see what this thing is developping.
First, I want to receive my motor, try it with the pod and the controller and report on my finding with the Teres pulley (I have one in stock already). Once is it confirmed that it is working correctly at 33rpm, then the Teres will still be an option.
Otherwise, we will all have to go the custom pulley road.
In the mean time, the pulleys money stay in my PayPal account.
First, I want to receive my motor, try it with the pod and the controller and report on my finding with the Teres pulley (I have one in stock already). Once is it confirmed that it is working correctly at 33rpm, then the Teres will still be an option.
Otherwise, we will all have to go the custom pulley road.
In the mean time, the pulleys money stay in my PayPal account.
The pulley looks easy enough I suggest a 2mm thread from the top so you can use it to pull off the pulley. I may have to order in a smaller micro boring bar to start the bore to ensure concentricity. I can ream the hole .001 under-size which is a tight press fit, it would most likely be better to ream it at 3mm since size on size works as an interference fit. Slight warming of the pulley would make it slip on easy.
I actually would prefer to make separate string and belt pulleys for the people that would want each type. This would lower the mass in both applications.
For something this accurate I prefer to use 7575 T6 aluminum, it is much harder and stronger.
I actually would prefer to make separate string and belt pulleys for the people that would want each type. This would lower the mass in both applications.
For something this accurate I prefer to use 7575 T6 aluminum, it is much harder and stronger.
Its great that we are on track again!
I would like to add:
If we are going to use tape we cannot use crown pulleys. This according to Vinyl-Addict who originally designed the pulley for a rubber belt. It has been reported that the crown pulleys cups the VHS tape belt. This problem would be exacerbated by using the thicker McCormick holographic tape. I guess the original GB did not really pursue using mylar tape as a belt as it was only in its infancy.
It has been recommended that we anodize the pulley for higher cf and prevent oxidation.
The design requires a tolerance of .0005".
17mm is the recommend diameter for optimum performance for 300mm platters, I'll be using a 311mm platter. I would assume that the majority using a tape drive will not be using a sub platter. Otherwise, there is the Teres.
That would be ideal no one will be happy with a one-size-fits-all approach. The string pulley looks good I might get one of those too😀 . How about multiple strings? Are there any provisions for easy removal?
I would like to add:
If we are going to use tape we cannot use crown pulleys. This according to Vinyl-Addict who originally designed the pulley for a rubber belt. It has been reported that the crown pulleys cups the VHS tape belt. This problem would be exacerbated by using the thicker McCormick holographic tape. I guess the original GB did not really pursue using mylar tape as a belt as it was only in its infancy.
It has been recommended that we anodize the pulley for higher cf and prevent oxidation.
The design requires a tolerance of .0005".
17mm is the recommend diameter for optimum performance for 300mm platters, I'll be using a 311mm platter. I would assume that the majority using a tape drive will not be using a sub platter. Otherwise, there is the Teres.
Greg Nuspel said:
That would be ideal no one will be happy with a one-size-fits-all approach. The string pulley looks good I might get one of those too😀 . How about multiple strings? Are there any provisions for easy removal?
I will tap the top with a 2.5 mm thread to allow a screw to be used as a puller to take the pulley off. No crown is even easier for the tape pulley. Multiple strings can be done as well I need more information though.
Tap? Could be use a gear puller that pulls from the bottom of the pulley
An externally hosted image should be here but it was not working when we last tested it.
Greg Nuspel,
Opinions on collet type mount. Which has better concentricity?
We just have to get everybody together. I think you've solved a major hurdle by offering to do the string and tape separately.
Opinions on collet type mount. Which has better concentricity?
We just have to get everybody together. I think you've solved a major hurdle by offering to do the string and tape separately.
Collet mount is expensive, the easiest size to get that would fit this application would be an ER-8 Collet. I can find out what a large order of 50 would cost but I predict it would be at least the price of the current pulley alone. You wouldn't want to use inexpensive collets as the run-out would be too much and unpredictable.
The reason for the tapped hole to be used for a puller is that everyone doesn't have a proper puller.
The reason for the tapped hole to be used for a puller is that everyone doesn't have a proper puller.
Greg Nuspel said:
Those mini gear pullers are readily available in hobby shops around $10.
ER-8 Collets, are they available in a lightweight alloy?