replacement motor for 6N?

[cymbalism]

i was contemplating replacing the motor in my 6N with one that would allow 33rpm and 45rpm. as i stated before, it cuts at 45rpm and 78rpm but i have zero use for 78 and would definately be able to use 33.

does anyone know what kind of motor i could use to replace the one i currently have and be able to cut at 33 and 45? i'm sure there's some motor out there which would allow it, i'm just looking for ideas and models that would work with the proper shafts etc.

lemme know!

[TotalSonic]

Instead of a new motor it seems it could be easier to get a different sized idler wheel to replace the 78rpm one. I'm not sure of the size you need - but if you measured the 78rpm and 45rpm idler wheels you should be able to calculate it - and then maybe get a machine shop to fabricate one for you.

Best regards,
Steve Berson

[markrob]

Instead of a new motor it seems it could be easier to get a different sized idler wheel to replace the 78rpm one. I'm not sure of the size you need - but if you measured the 78rpm and 45rpm idler wheels you should be able to calculate it - and then maybe get a machine shop to fabricate one for you.

Best regards,
Steve Berson

Hi Steve,

The idler wheel diameter has no effect on platter speed. Its determined by the shaft speed of the motor and the ratio of the diameters of the platter and the motor shaft (that's why they call it an idler). To change speeds on the 6N, the shaft bushing has two different diameters. The the speed selection lever engages one of two idler wheels, set at the correct height to contact the correct step diameter. What tommie needs to do, is remove the stepped motor shaft bushing and have the diameter of the 45 RPM section turned down slow down the speed to 33. It should have a allen set screw holding to the motor shaft. Mine measures .300" diameter for the 33 RPM speed. I think Presto sold an aftermarket bushing to make the conversion from 33 to 45, so this is what he may have installed on his 6N.

Mark

[TotalSonic]

Hi Steve,

The idler wheel diameter has no effect on platter speed. Its determined by the shaft speed of the motor and the ratio of the diameters of the platter and the motor shaft (that's why they call it an idler). To change speeds on the 6N, the shaft bushing has two different diameters. The the speed selection lever engages one of two idler wheels, set at the correct height to contact the correct step diameter. What tommie needs to do, is remove the stepped motor shaft bushing and have the diameter of the 45 RPM section turned down slow down the speed to 33. It should have a allen set screw holding to the motor shaft. Mine measures .300" diameter for the 33 RPM speed. I think Presto sold an aftermarket bushing to make the conversion from 33 to 45, so this is what he may have installed on his 6N.

Mark

Mark -
thanks for the info and for correcting my misunderstanding.

Best regards,
Steve Berson

[cymbalism]

What tommie needs to do, is remove the stepped motor shaft bushing and have the diameter of the 45 RPM section turned down slow down the speed to 33. It should have a allen set screw holding to the motor shaft. Mine measures .300" diameter for the 33 RPM speed. I think Presto sold an aftermarket bushing to make the conversion from 33 to 45, so this is what he may have installed on his 6N.

Mark

hey mark

i wonder how hard it would be to get a machinist to fabricate one for 33 and 45 and what the dimensions would be. the motor on it works fantastic, fixed pitch and all - just would be nice to cut an album at 33 instead of spreading it out over 3 plates at 45 hehe

[markrob]

Hi tommie,

Since you have a bushing that has 45, just measure it. I calculate that you need a diameter of .405" for 45 RPM based on my measurment of .300" for 33 1/3 RPM. If you can get the current bushing off of the motor shaft (sometimes hard), you can have a new one made. Or, just turn down your exisitng one so that the 45 step becomes 33 (.300") and the 78 step becomes 45 (.405"). In my case, I have a standard 33/78 machine, so I made a sleeve to fit over the top section (33) and I can get 45.

[cymbalism]

Hi tommie,

Since you have a bushing that has 45, just measure it. I calculate that you need a diameter of .405" for 45 RPM based on my measurment of .300" for 33 1/3 RPM. If you can get the current bushing off of the motor shaft (sometimes hard), you can have a new one made. Or, just turn down your exisitng one so that the 45 step becomes 33 (.300") and the 78 step becomes 45 (.405"). In my case, I have a standard 33/78 machine, so I made a sleeve to fit over the top section (33) and I can get 45.

the bushing is silver and is wide on the bottom and narrow at the top. i'm assuming it's not an original bushing otherwise it would be 33/78. so you're saying if i can get the busing off with the allen wrench and take it to a machinist, they would just have to make it .300" and .405"? the motor should adjust appropriately after that? or would it be easy just to get an original 33/78 bushing and buy the 45 adapter?

[markrob]

Hi,

That's how I see it. If you have acess to a dial caliper or micrometer, you could measure the two steps and see if the numbers agree with mine (78 RPM should be .702"). Should be no need to change the motor. Finding a 33/78 bushing by itself will probably be difficult. I'm not sure how hard it will be to get the current bushing off the motor shaft.

One other note. If you find a machinst to do this, you might want to have him cut the steps a few thousandths oversize and check the speeds with a strobe disk. That way if you are off, you can have him trim it a bit to get the exact speed. Consider that at 33 RPM with a size of .300" dia. a .003" error is 1% or 17 cents in pitch. Assuming the current 45 speed is accurate enough for you, have him use the current size of the top (45 RPM) step as the number to use for the bottom step on the new bushing. Make sure he understands that the bushing should have little or no measured runnout or you will have flutter problems. Hope this makes sense.

Mark

[Doug6N]

Hi:

Due to some issues I wound having a 33 & 78 motor drive made and a separate one for 45 I did this because I do cut some 78's.

Now what I did was carry the cutter up to the machinist along with a strobe disc. And we took those pulleys off and on a few times slightly polishing each time until speed was exact. It was a machine shop that specialized in precision manufacturing and he understood the importance of it being as near absolutely true as possible.


Works perfect no issues at all with the work done.

Doug

[cymbalism]

i resolved my issue - 33, 45 and 78 now - whoo hoo! too bad i dont know anyone i can cut a 78 for now