Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
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
Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
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 on behalf of Chuck Guzis via cctalk 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
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
Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
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 on behalf of Charles Dickman via cctalk 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@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?
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@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?
Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
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 on behalf of Chuck Guzis via cctalk 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: >>> 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? 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
Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
On 11/10/18 12:33 PM, Fred Cisin 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. > 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? 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
Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
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?
Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
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
Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
On Sat, Nov 10, 2018 at 7:42 PM 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. 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 >
Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
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 on behalf of Chuck Guzis via cctalk 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
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
Re: AW: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B
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 on behalf of Guy Dunphy via cctalk 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 +, Riesen Thomas wrote: >Guy, >I am looking for small motor pulley ... see pic ... >Regards >Thomas > >-Ursprüngliche Nachricht- >Von: Guy Dunphy [mailto:gu...@optusnet.com.au] >Gesendet: Samstag, 10. November 2018 13:25 >An: Riesen Thomas ; General Discussion: On-Topic and >Off-Topic Posts >Betreff: Re: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B > >At 12:03 PM 10/11/2018 +, 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 lng 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" >
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 +, Riesen Thomas wrote: >Guy, >I am looking for small motor pulley ... see pic ... >Regards >Thomas > >-Ursprüngliche Nachricht- >Von: Guy Dunphy [mailto:gu...@optusnet.com.au] >Gesendet: Samstag, 10. November 2018 13:25 >An: Riesen Thomas ; General Discussion: On-Topic and >Off-Topic Posts >Betreff: Re: 50Hz Pulley for 8" Floppy Drive Mitshubishi M2894-63B > >At 12:03 PM 10/11/2018 +, 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 lng 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" >
