MC900 Pulley Problem

[Big Shed]

Almost finished my pesky piece of olive yesterday when disaster struck!:((

The MC900 lathe started to make a knocking noise and wouldn't speed up to higher speeds and it was easy to slow down by puttig a little pressure on the work.

Invetsigated this morning and it appears there is a problem with the drive pulley. There are 2 grub screws in the half pulley closest to the motor, one is missing and the other was loose. Tightened that one, which fixed the knocking sound, but still haven't got drive at hiher speeds. At the lower speeds the belt is reasonably tight but as I go higher the headstock pulleys seaprate and the belt goes slack.

Not being an engineering type, I am assuming that somehow the drive pulley is supposed to take up this slack?

Anybody out there like to enlighten me as to the problem?

Many thanks.

[arose62]

My first guess is that it's due for a general cleanup and some squirting of Inox.

The split pulley on the headstock shaft is opened and closed by the speed control handle.

The split pulley on the motor shaft is opened by the belt pulling into it, and closed by a big spring on the end of the shaft.

Sounds like the split pulley on the motor shaft is sticking (stuck open?), and needs some Inox on the shaft.

High speed = motor pulley closed (belt riding up high) and headstock pulley open (belt riding low down in the groove).

Low speed is the opposite.

See here for pic of rear pulley.
http://people.aapt.net.au/~rosefamily/RearSplitPulley.jpg

Cheers,
Andrew

[petersemple]

It is also possible that the pulley halves have become misaligned, or the knocking has raised a bit of a burr on one half that is stopping the two halves from slipping smoothly past each other. If that is the case then I think a bit of detective work to find the problem and a quick filing can solve it.

Peter

[Big Shed]

Thank you gentlemen, removed the 2 half pulleys from the motor shaft and as you said, it was "gunk" on the shaft. Cleaned up the shaft and inside the pulley halves. Lubricated with a bit of motor oil, don't have Inox, and it works fine now. Both pulleys expand and contract as advertised.

Noticed in the process that on highest and lowest speeds the belt almost comes off the closed pulley, it is obviously not the original belt and appears too long. It is marked Mitsubishi 10x585 M-23. So will have to look for a slightly shorter belt as well as a replacement grub screw.

Have also cleaned and lubricated the head stock pulley and speed change mechanism, works much smoother now!

Many thanks for your help.:2tsup:

[Calm]

Occasionally mine (the same as the above photo) does that too. I just spray a bit of CRC or something on it and it usually frees up.

I find if you set the speed to the highest the belt will be slack and you may need to gently tap the pulley with a lump of wood to free it intially but then the CRC should do its job.

[HappyHammer]

Come on BS not long to go until the judging thread starts.....:o

HH.

[Big Shed]

Come on BS not long to go until the judging thread starts.....:o

HH.

Now you tell me:doh:

[DJ’s Timber]

Yeah, I'm still waiting for those photos BS :q:U

[Big Shed]

Yeah, I'm still waiting for those photos BS :q:U

Winging their way across cyberspace as I type:2tsup:

[DJ’s Timber]

Got them :2tsup:

[arose62]

So will have to look for a slightly shorter belt as well as a replacement grub screw.

Would it work to put a spacer between the motor and the headstock casing, to pack it out a bit and take up the belt slack?

Cheers,
Andrew

[Tornatus]

I find if you set the speed to the highest the belt will be slack and you may need to gently tap the pulley with a lump of wood to free it intially but then the CRC should do its job.

Just saw this post - DANGER, WILL ROBINSON!

I agree with Calm about lubricant (Inox is best IMHO - no petrochemical residue), but be very wary of tapping these pulleys with anything, however gently.

I used to work in a business that sold these lathes, and we frequently saw the disastrous results of people becoming impatient with sticking pulleys - they are quite low-grade aluminium castings (this is a cheap lathe we are talking about) and they will break at the slightest provocation, whether from impact or from being levered apart with screwdrivers, etc.

If pulleys stick, the best approach is to thoroughly clean the area, then soak the shafts with penetrative lubricant, leave them a good while, then very gently try moving the pulley halves by hand - a lot of wiggling is much safer than applying mechanical force of any kind. Once they are free, the best prevention of further problems is regular cleaning and lubrication - the definitive test is that you should be able to move the speed change lever with one finger (with the power on, of course).

BTW, from memory the correct v-belt for this lathe is coded A22 - maybe another MC900 user could confirm.

[TTIT]

.......... low-grade aluminium castings (this is a cheap lathe we are talking about) and they will break at the slightest provocation, whether from impact or from being levered apart with screwdrivers, etc...............I'll go along with that!:o I accidentally dropped one from less than 3' on to the concrete and broke a chunk out of the side :~:C



.........BTW, from memory the correct v-belt for this lathe is coded A22 - maybe another MC900 user could confirm.Almost right - A22 is not the specified belt but I found it worked better using an A22 and outlasted the standard one a hundred fold!:U

[woodwork wally]

Hi Just a wee note to say no to motor oil on the pulleys as it seems to increase the amount of down time to ungunk the system Innox is probably the best but there are other silicone sprays that work well and are occasionally on special and dont seem to have the ability to gunk up with the fine sawdust . Hope this helps regards WW Wally

[Big Shed]

BTW, from memory the correct v-belt for this lathe is coded A22 - maybe another MC900 user could confirm.


Have now replaced the missing grub screw on the motor pulley, should have 2 but it only had one.

As I noted earlier the belt that is on the lathe rides quite high on the motor pulley, actually half of the belt profile height sticks above the pulley.

It is a Mitsuboshi M23 10x585, I obtained an A22 (Mitsuboshi also) 13x560 and put this on the lathe. This gives a lower low end speed, but has reduced the top speed, it also doesn't ride as high in the motor pulley, but sticks sligtly above the head stock pulley.

It appears that neither of these belts is the exact belt required, does someone know what the correct belt for these MC900 lathes is?

[Calm]

I think you will find they are actually an "M" section belt not a "A" section.

[Big Shed]

I think you will find they are actually an "M" section belt not a "A" section.

I think you may be right, just looked at a similar Grizzly lathe and it uses a M24 belt.

Might put the M23 belt back on till I get to the bottom of this, don't know whether the A22 belt will do any harm.

Anybody know the difference between A and M type belts, I assume it is the profile?

[Tornatus]

Sorry if I gave you a bum steer on the A22 belt, BS - now you've got me keen to find out which would be the best fit. The belts on my lathe so far have just been the el cheapo ones supplied by CarbaTec, and they have no code markings at all. They wear out rapidly, although I have had much longer service from mine since I disassembled the pulleys (carefully!) and polished the inner faces with wet&dry then metal polish to remove all the machining marks, etc which contribute to wear.

Surely someone amongst our fellow forumites has the engineering know-how to set us straight...:?

[Big Shed]

Sorry if I gave you a bum steer on the A22 belt, BS - now you've got me keen to find out which would be the best fit. The belts on my lathe so far have just been the el cheapo ones supplied by CarbaTec, and they have no code markings at all. They wear out rapidly, although I have had much longer service from mine since I disassembled the pulleys (carefully!) and polished the inner faces with wet&dry then metal polish to remove all the machining marks, etc which contribute to wear.

Surely someone amongst our fellow forumites has the engineering know-how to set us straight...:?

Hey, no problem, only cost $5.20. It still works, but instead of riding high on the motor pulley it rides high on the headstock spindle pulley. It is certainly a very solid and substantial belt.

Have been searching the web, but can't find any references to either the specified belt for MC900 or specs for the M23 and A22.

[TTIT]

I preferred the A22 because the lathe ran slightly slower with it which was better for larger items and I never turned at the top end anyway :shrug: