10 Nov
2018
10 Nov
'18
6:19 a.m.
Ok. Those are quite small. So you have one? Or those are not yours?
If you have one, and a way to accurately measure it, making more will be easy for anyone
with a lathe.
I could do it, but surely you can find a machinist closer to home?
Guy
At 01:03 PM 10/11/2018 +0000, Riesen Thomas wrote:
Guy,
I am looking for small motor pulley ... see pic ...
Regards
Thomas
-----Urspr?ngliche Nachricht-----
Von: Guy Dunphy [mailto:guykd at optusnet.com.au]
Gesendet: Samstag, 10. November 2018 13:25
An: Riesen Thomas <thomas.riesen at predata.ch>; General Discussion: On-Topic and
Off-Topic Posts <cctalk at classiccmp.org>
Betreff: Re: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
At 12:03 PM 10/11/2018 +0000, you wrote:
Hi all
Any suggestions where to find two 50Hz-Pulleys for the 8" Floppy drive
Mitsubishi M2894-63B?
If there also the appropriate ribbon gummies available, I would be very
happy.
Regards
Thomas
Do you know what they look like, and the dimensions?
Because I have these. http://everist.org/pics/misc/IMG_1655_pulley_800.jpg
_Maybe_ they were off Mitsubishi drives, not sure. Had them in a box of floppy drive
related bits for a loooong time, and have no recollection of where they came from.
These are 49.0 mm OD, hole 4.7 mm dia. And this is Australia, with 50Hz mains.
Guy
Attachment Converted: "f:\email\attach\Pully_8Zoll_02.jpg"
Attachment Converted: "f:\email\attach\Pully_8Zoll_01.jpg"
10 Nov
10 Nov
7:55 a.m.
Typically, both the motor pulley and belt are changed as a set to keep the distance from
motor to flywheel the same.
In my younger days, a friend and I ground down a motor pulley, on a 50 Hz Shugart 800, to
be a 60 Hz. We used a file while the motor ran. After getting the right size, we had to
file mounting holes for the motor to keep the same belt. It was not the best way but we
couldn't afford a new drive and we got the drive cheap, from surplus.
If you change the flywheel, the distance will be to great to use the same belt or even
close to the same belt. It may not even fit in the area allowed for the flywheel.
According to the manual, for this drive, only the motor pulley needs to be changed as
there is enough adjustment to use the same belt.
Dwight
________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Guy Dunphy via cctalk
<cctalk at classiccmp.org>
Sent: Saturday, November 10, 2018 6:19 AM
To: Riesen Thomas; General Discussion: On-Topic and Off-Topic Posts
Subject: Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
Ok. Those are quite small. So you have one? Or those are not yours?
If you have one, and a way to accurately measure it, making more will be easy for anyone
with a lathe.
I could do it, but surely you can find a machinist closer to home?
Guy
At 01:03 PM 10/11/2018 +0000, Riesen Thomas wrote:
Guy,
I am looking for small motor pulley ... see pic ...
Regards
Thomas
-----Urspr?ngliche Nachricht-----
Von: Guy Dunphy [mailto:guykd at optusnet.com.au]
Gesendet: Samstag, 10. November 2018 13:25
An: Riesen Thomas <thomas.riesen at predata.ch>; General Discussion: On-Topic and
Off-Topic Posts <cctalk at classiccmp.org>
Betreff: Re: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
At 12:03 PM 10/11/2018 +0000, you wrote:
Hi all
Any suggestions where to find two 50Hz-Pulleys for the 8" Floppy drive
Mitsubishi M2894-63B?
If there also the appropriate ribbon gummies available, I would be very
happy.
Regards
Thomas
Do you know what they look like, and the dimensions?
Because I have these. http://everist.org/pics/misc/IMG_1655_pulley_800.jpg
_Maybe_ they were off Mitsubishi drives, not sure. Had them in a box of floppy drive
related bits for a loooong time, and have no recollection of where they came from.
These are 49.0 mm OD, hole 4.7 mm dia. And this is Australia, with 50Hz mains.
Guy
Attachment Converted: "f:\email\attach\Pully_8Zoll_02.jpg"
Attachment Converted: "f:\email\attach\Pully_8Zoll_01.jpg"
8:32 a.m.
On 11/10/18 7:55 AM, dwight via cctalk wrote:
Typically, both the motor pulley and belt are changed
as a set to keep the distance from motor to flywheel the same.
In my younger days, a friend and I ground down a motor pulley, on a 50 Hz Shugart 800, to
be a 60 Hz. We used a file while the motor ran. After getting the right size, we had to
file mounting holes for the motor to keep the same belt. It was not the best way but we
couldn't afford a new drive and we got the drive cheap, from surplus.
If you change the flywheel, the distance will be to great to use the same belt or even
close to the same belt. It may not even fit in the area allowed for the flywheel.
According to the manual, for this drive, only the motor pulley needs to be changed as
there is enough adjustment to use the same belt.
I was gifted a brand-new Qume 842 220V 50Hz drive many years ago. The
220V was no problem--I had a dual-primary transformer on the power
supply, so it could be reconfigured as a 240V autotransformer and still
have enough capability for the drive electronics. The problem was the
60Hz line frequency. Essentially, the motor turns somewhat faster, so
you need a smaller motor pulley. I calculated what I needed and found a
flanged toothed pulley for a timing belt that was exactly the right
size. While the original motor pulley was crowned, the timing pulley
worked exactly as calculated. It was not necessary to change the drive
belt--the size difference was small enough that it could be swamped out
by loosening the motor mounting bolts and adjusting.
I still have the drive today--and it still works.
--Chuck
11:42 a.m.
He needs a larger pulley if going from 60 to 50 ( as a motor pulley ). It needs to be 20%
bigger because the motor turns slower on 50 Hz. 6/5 to be exact.
Dwight
________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Chuck Guzis via cctalk
<cctalk at classiccmp.org>
Sent: Saturday, November 10, 2018 8:32 AM
To: dwight via cctalk
Subject: Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
On 11/10/18 7:55 AM, dwight via cctalk wrote:
Typically, both the motor pulley and belt are changed
as a set to keep the distance from motor to flywheel the same.
In my younger days, a friend and I ground down a motor pulley, on a 50 Hz Shugart 800, to
be a 60 Hz. We used a file while the motor ran. After getting the right size, we had to
file mounting holes for the motor to keep the same belt. It was not the best way but we
couldn't afford a new drive and we got the drive cheap, from surplus.
If you change the flywheel, the distance will be to great to use the same belt or even
close to the same belt. It may not even fit in the area allowed for the flywheel.
According to the manual, for this drive, only the motor pulley needs to be changed as
there is enough adjustment to use the same belt.
I was gifted a brand-new Qume 842 220V 50Hz drive many years ago. The
220V was no problem--I had a dual-primary transformer on the power
supply, so it could be reconfigured as a 240V autotransformer and still
have enough capability for the drive electronics. The problem was the
60Hz line frequency. Essentially, the motor turns somewhat faster, so
you need a smaller motor pulley. I calculated what I needed and found a
flanged toothed pulley for a timing belt that was exactly the right
size. While the original motor pulley was crowned, the timing pulley
worked exactly as calculated. It was not necessary to change the drive
belt--the size difference was small enough that it could be swamped out
by loosening the motor mounting bolts and adjusting.
I still have the drive today--and it still works.
--Chuck
12:05 p.m.
On Sat, Nov 10, 2018 at 7:42 PM dwight via cctalk <cctalk at classiccmp.org> wrote:
He needs a larger pulley if going from 60 to 50 ( as a motor pulley ). It needs to be 20%
bigger because the motor turns slower on 50 Hz. 6/5 to be exact.
I like the way Tektronix handled this issue in the 8560 (service manual on
Bitsavers). They produced a 60Hz supply by chopping rectified and
smoothed mains, thus the incoming mains frequency does not matter.
An 8560 will work in the States or in Europe with no pulley changes.
-tony
12:27 p.m.
On 11/10/18 11:42 AM, dwight via cctalk wrote:
He needs a larger pulley if going from 60 to 50 ( as a
motor pulley ). It needs to be 20% bigger because the motor turns slower on 50 Hz. 6/5 to
be exact.
Dwight
No argument there--but the size increment is pretty small. Consider
that a typical motor pulley is about 19 mm in diameter, so a 20%
increase would be only about 23 mm.
One could also take Tony's approach and simply cobble up a
crystal-controlled 60Hz source for the motor. Shouldn't be too
difficult--I suspect that the motor doesn't draw more than about 30W.
If you had an excess of 12VDC, you could possibly use an inexpensive
inverter to do the job.
--Chuck
12:33 p.m.
> He needs a larger pulley if going from 60 to 50 (
as a motor pulley ).
> It needs to be 20% bigger because the motor turns slower on 50 Hz. 6/5
> to be exact.
On Sat, 10 Nov 2018, Chuck Guzis via cctalk wrote:
No argument there--but the size increment is pretty
small. Consider
that a typical motor pulley is about 19 mm in diameter, so a 20%
increase would be only about 23 mm.
Depending on the drive, WHICH pulley should be changed?
12:38 p.m.
On 11/10/18 12:33 PM, Fred Cisin via cctalk wrote:
The motor drive pulley is the easiest. You might even find a ready-made
one in an engineering findings catalog.
Alternatively, consider this YT video for a DIY frequency changer:
https://www.youtube.com/watch?v=mEiUt56elAw
--Chuck
> He needs a
larger pulley if going from 60 to 50 ( as a motor pulley
> ). It needs to be 20% bigger because the motor turns slower on 50 Hz.
> 6/5 to be exact.
On Sat, 10 Nov 2018, Chuck Guzis via cctalk wrote:
No argument there--but the size increment is
pretty small.? Consider
that a typical motor pulley is about 19 mm in diameter, so a 20%
increase would be only about 23 mm.
Depending on the drive, WHICH pulley should be changed?
4:46 p.m.
If the pulley diameter was 19.0mm, the new pulley would be exactly 22.8mm. It is a simple
ratio problem. The motors rotation is synchronous to the line frequency. It turns 50/60
too slow. To speed it up is 6/5. The speed of the belt is proportional to the radius of
the pulleys.
If it was a crowned belt, a fine tune can be done with the tension of the belt. A tighter
belt will run a little slower because most of it rides lower on the pulley. The tension on
the belt is the same everywhere, not counting bearing and drag on the disk. This means the
effective rate is determined, mainly, by the where the belt rides on the pulley.
Dwight
________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Chuck Guzis via cctalk
<cctalk at classiccmp.org>
Sent: Saturday, November 10, 2018 12:38 PM
To: Fred Cisin via cctalk
Subject: Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
On 11/10/18 12:33 PM, Fred Cisin via cctalk wrote:
The motor drive pulley is the easiest. You might even find a ready-made
one in an engineering findings catalog.
Alternatively, consider this YT video for a DIY frequency changer:
https://www.youtube.com/watch?v=mEiUt56elAw
--Chuck
> He needs a
larger pulley if going from 60 to 50 ( as a motor pulley
> ). It needs to be 20% bigger because the motor turns slower on 50 Hz.
> 6/5 to be exact.
On Sat, 10 Nov 2018, Chuck Guzis via cctalk wrote:
No argument there--but the size increment is
pretty small. Consider
that a typical motor pulley is about 19 mm in diameter, so a 20%
increase would be only about 23 mm.
Depending on the drive, WHICH pulley should be changed? 
27 Mar
27 Mar
12:58 p.m.
On Sat, Nov 10, 2018 at 3:27 PM Chuck Guzis via cctalk <
cctalk at classiccmp.org> wrote:
One could also take Tony's approach and simply
cobble up a
crystal-controlled 60Hz source for the motor. Shouldn't be too
difficult--I suspect that the motor doesn't draw more than about 30W.
If you had an excess of 12VDC, you could possibly use an inexpensive
inverter to do the job.
Never saw a floppy drive with an AC motor. In the past discussions about
50Hz vs 60Hz drive, I expected it to be a 120/240 VAC motor. So is it
actually a low voltage (synchronous) AC motor?
1:36 p.m.
Most all 8 inch drives were synchronous capacitive phased AC motors. That is until 3 phase
low voltage motors started showing up on 5.25 disk drives.
The ac motors on the 8 inch drives rarely had jumper options for 120/240V AC. Most were
fixed voltage and cycles. I can't recall any that I've seen that had a voltage
option.
Dwight
________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Charles Dickman via
cctalk <cctalk at classiccmp.org>
Sent: Wednesday, March 27, 2019 12:58 PM
To: Chuck Guzis; General Discussion: On-Topic and Off-Topic Posts
Subject: Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
On Sat, Nov 10, 2018 at 3:27 PM Chuck Guzis via cctalk <
cctalk at classiccmp.org> wrote:
One could also take Tony's approach and simply
cobble up a
crystal-controlled 60Hz source for the motor. Shouldn't be too
difficult--I suspect that the motor doesn't draw more than about 30W.
If you had an excess of 12VDC, you could possibly use an inexpensive
inverter to do the job.
Never saw a floppy drive with an AC motor. In the past discussions about
50Hz vs 60Hz drive, I expected it to be a 120/240 VAC motor. So is it
actually a low voltage (synchronous) AC motor?
2:07 p.m.
On 3/27/19 1:36 PM, dwight via cctalk wrote:
Most all 8 inch drives were synchronous capacitive
phased AC motors. That is until 3 phase low voltage motors started showing up on 5.25 disk
drives.
The ac motors on the 8 inch drives rarely had jumper options for 120/240V AC. Most were
fixed voltage and cycles. I can't recall any that I've seen that had a voltage
option.
Dwight
I picked up a new Qume 842 for 220V 50 Hz and simply substituted a
flanged timing pulley for the crowned one, adjusted for the frequency
variation. I powered it from the power supply transformer primaries
hooked as an autotransformer to give 240VAC. Worked just fine.
--Chuck
4:06 p.m.
A friend an I did almost the same thing. We used the transformer primary from another box
as an auto transformer and used a file to grind the motor pulley down. We did have to file
the mounting slots some as well. It worked fine.
This was about 25 years ago.
Dwight
________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Chuck Guzis via cctalk
<cctalk at classiccmp.org>
Sent: Wednesday, March 27, 2019 2:07 PM
To: dwight via cctalk
Subject: Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
On 3/27/19 1:36 PM, dwight via cctalk wrote:
Most all 8 inch drives were synchronous capacitive
phased AC motors. That is until 3 phase low voltage motors started showing up on 5.25 disk
drives.
The ac motors on the 8 inch drives rarely had jumper options for 120/240V AC. Most were
fixed voltage and cycles. I can't recall any that I've seen that had a voltage
option.
Dwight
I picked up a new Qume 842 for 220V 50 Hz and simply substituted a
flanged timing pulley for the crowned one, adjusted for the frequency
variation. I powered it from the power supply transformer primaries
hooked as an autotransformer to give 240VAC. Worked just fine.
--Chuck
4:26 p.m.
On 3/27/19 4:06 PM, dwight wrote:
A friend an I did almost the same thing. We used the
transformer primary
from another box as an auto transformer and used a file to grind the
motor pulley down. We did have to file the mounting slots some as well.
It worked fine.
This was about 25 years ago.
Dwight
Well, I bought two pulleys, so if anyone has an 842 220V 50Hz unit they
want to try this on, I'm happy to part with one.
--Chuck
2097
days inactive
2234
days old
13 comments
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