|Jim W||25/06/2020 22:09:21|
2 forum posts
I'm recently and very happily back in the world of model engineering after a break of 20 odd years. I recently bought a very nice Myford ML7 and Hobbymat BFE65 from an elderly gent who's had them for some decades.
I saw the mill running and all was fine but when I got it home, it makes an insane level of noise when switched on as if the gears are stripping.
I popped off the speed control handles and left panel so I could have a look at the gearbox and all seems fine inside, I am not entirely sure what I need to be looking for...can anyone give me any hints or tips?
The machine is a geared version
Plenty of grease inside
Previous owner fitted grub screws to speed control levels to prevent them popping out of gear
The spindle turns in all speeds and seems to have power its just this deafening noise that worries me!
Many thanks in advance, people.
|Paul Kemp||26/06/2020 13:13:35|
|580 forum posts|
I think the mill head has the same motor as the lathe. Check the motor fan cover, it may have been displaced in the move? That makes a dreadful racket! Just a thought.
|roy entwistle||26/06/2020 16:11:06|
|1269 forum posts|
If you can I would check the fan as well
|146 forum posts|
Agree with Paul, check the motor fan cover first. (Also, and profuse apologies if you know this, but the gears must be carefully selected before startng by turning the spindle back and forth as the engagement levers are operated until they are felt to go fully "home".. )
If you do need to check the action of the gear assembly, you need to remove the opposite cover - the one with the downfeed lever.. (Isolate the power - Remove the screw and washer, pull off the lever and dial, remove the (parallel/straight) pin and any washer or shim, then the cover screws - note that one may be shorter to avoid fouling the motor screw at the upper rear).
With the cover removed and rotating the spindle backwards & forwards by hand, switch each speed selector lever into it's high & low range - each lever acts to move a steel dog (keyed to it's respective shaft) into or out of mesh with one of a pair of (either phenolic, or ?acetal) gears which lie above and below it, and are free to rotate on the shaft.
The upper lever moves the dog between the pair on the output shaft to the spindle, the lower operates that between the pair on the countershaft which picks up the drive from the motor.
In each lever position, only one of the gears should be "connected" with the spindle via the dog - the "freewheeling" gear that is not engaged with the dog MUST still be CORRECTLY engaged with it's respective pinion on the other shaft - i.e., all four resin or plastic gears must sit squarely, evenly, and consistently, and be in constant mesh with their mating gear, irrespective of the position of the dog (- it is not unheard of for the (white) plastic gears to come loose from their internal bronze bushes, this case usually evidenced by wobbling or vertical misalignment that is obvious to the eye.
Which brings me back to the intruction regarding wiggling the spindle to ensure engagement of the dogs with the gears - the dog itself comprises only a simple tongue , and so the gears must be manually rotated to "pick up" the corresponding slots in the pinion to ensure correct drive before the motor is started.
I hope that "your" noise is just a lack of proper engagement.. if the "grub screw" detents that you mention are located in the lever-bosses, they a standard fitment.
Oh, and do be mindful of aligning the selector lever forks with their slots in the dogs when you reassemble the left hand cover.. can't remember what the lever positions have to be in, without checking.. will be obvious, I'm sure..
Let us know how how things go..
Edited By DiogenesII on 26/06/2020 16:30:05
|Jim W||26/06/2020 20:57:26|
2 forum posts
Thank you so much. I knew this would be the right forum to join...there's clearly a huge amount of knowledge here.
I will have a look tomorrow and report back on how it goes. The fan guard on the motor makes sense though..it does sound like that.
Have a great evening all.
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