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  1. #166
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi FamilyGuy, Guys,

    Well I've fixed the mill ! I made a new bush in bronze to replace the original one. The fine feed gears now mesh again, but its only a couple of mm. One of the two gears could do with being a few mm larger in diameter.

    Mill Bush_18-02-2020.JPG

    I had a wonder around the scrap yard Monday and came home with an old electric tile saw. Until I pull it apart I don't know if the motor will be of any use. It did sound very rough and noisy, a bit like an electric drill. It has a four inch diamond edged blade on it that waggles from side to side about a 1/4" inch, so the bearings are shot.

    I also picked up about a foot of 3/4" inch diameter bronze rod for a couple of pounds. It should be OK for making a thumb screw or two.

    More later
    Last edited by BaronJ; 19th Feb 2020 at 03:58 AM. Reason: Added Picture
    Best Regards:
    Baron J.

  2. #167
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Thumbs up Tile saw motor !

    Hi Guys,

    Well yesterday I picked up an old ceramic tile saw. Mainly out of curiosity to see if the motor in it would be suitable for the wheel head of the grinder.

    18-02-2020-004.jpg 18-02-2020-005.jpg 18-02-2020-006.jpg
    18-02-2020-007.jpg

    Well this is it ! The blade is held by a nut on the end of the shaft. The blade is obviously not the correct one for this machine. Its been modified to take a 100 mm diameter blade, someone has cut a slot in the bottom to accommodate the slightly larger one. I suspect that the original blade would have been an expensive 80 mm diameter one, whilst the larger blade only costs a pound.

    18-02-2020-008.JPG 18-02-2020-009.jpg

    Evidence of butchery ! A piece of aluminium has been hot melt glued across the bottom to close the slot cut in it and stop the water from running out.

    18-02-2020-010.JPG 18-02-2020-012.jpg 18-02-2020-011.JPG 18-02-2020-013.JPG

    The motor before and after extraction. As can be seen it is an open frame universal brush motor with an integral gearbox. The motor runs just fine. At this moment I don't know what the speed of the output shaft is. The whole thing is fastened by two M4 screws and the red plate in the middle of the body. The green thing is an interference suppression filter, designed to stop electrical noise from the motor brushes.

    According to the data printed on the motor, its serial No: 644032, 230 volt 50Hz, I'm guessing 155 Watts.

    I'm debating whether this motor is going to be suitable for use with the grinder. Its going to need a new bearing on the output shaft in order to make it usable. It will also need to be covered in order to make it safe.

    Some more work to do.

    Thanks Guys.
    Best Regards:
    Baron J.

  3. #168
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,541

    Default

    I managed to pick up a (new) small bench grinder from Bunnings the other day for all of $35. At that price, salvaging an old motor from something becomes marginal.

    Michael

  4. #169
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
    Posts
    2,651

    Default

    Quote Originally Posted by Michael G View Post
    I managed to pick up a (new) small bench grinder from Bunnings the other day for all of $35. At that price, salvaging an old motor from something becomes marginal.

    Michael
    If it’s an Ozito one you might find you change your mind if you ever try and fit a different wheel. Shoulder on the shaft would be lucky if it’s 1mm high, the stock wheel flanges unlikely to be that thick.
    I got mine (brand new) for $20 and I’d say it’s marginal value even at that price!!
    The belt sander version is 240W vs 150W for the grinder, and probably better value IMO even though it retails at twice the price ($70). Haven’t checked out the shaft arrangement on that one though - I’m running it straight out of the box for light deburring etc.

    Steve

  5. #170
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Guys,

    Lidl or maybe Aldi over here did a cheap grinder a short while ago for £20 (£19.99) 150 watt motor. 100 mm wheel. No sign of being able to get any spares. I've noticed this with several items, spare consumables are just not easily obtainable. Unless you buy them from China !
    Best Regards:
    Baron J.

  6. #171
    Join Date
    Nov 2019
    Location
    Brisbane
    Age
    69
    Posts
    452

    Default Bench grinder

    Hello from The Old Goat.
    A few things to consider when buying a bench grinder.
    Duty cycle is high when grinding tools. My grinder can run for 15mins strait at times.
    Number of stop starts in an hour. The cheaper units are rated at about 6 starts per hour or the caps fail.
    The shaft is usually welded to the rotor either end and mostly on the same side of the shaft. The shaft ends up like a bananna.
    Flanges are not suitable for toolroom wheels.
    Spend a few dollars and buy a good grinder. I paid $80 for my first grinder, 35 years ago. It has survived a flogging.
    You need something with a bit of weight to absorb vibration. My last grinder for big drills is mounted to a heavy piece of white cutting board material. That makes a big difference. You can use a thick bit of chipboard as well but it won't last as good.
    BC

  7. #172
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Bernie,

    Quote Originally Posted by steamloco1954 View Post
    Hello from The Old Goat.
    The shaft is usually welded to the rotor either end and mostly on the same side of the shaft. The shaft ends up like a bananna.
    BC
    I've picked up on this comment because it is confusing and gives the impression that the shaft is welded on in two halfs.

    The rotors on every electric motor I've ever seen are a one piece shaft with a stack of laminations pressed on to it, the end laminations may be welded to the shaft to prevent any movement. On an induction motor the lamination stack has a cast alloy frame around it, usually called a "Squirrel Cage" containing the conductor bars.

    Anyway thanks for reading my Brooks TCG posts.
    Best Regards:
    Baron J.

  8. #173
    Join Date
    Nov 2019
    Location
    Brisbane
    Age
    69
    Posts
    452

    Default Bench grinder woes.

    Quote Originally Posted by BaronJ View Post
    Hi Bernie,



    I've picked up on this comment because it is confusing and gives the impression that the shaft is welded on in two halfs.

    The rotors on every electric motor I've ever seen are a one piece shaft with a stack of laminations pressed on to it, the end laminations may be welded to the shaft to prevent any movement. On an induction motor the lamination stack has a cast alloy frame around it, usually called a "Squirrel Cage" containing the conductor bars.

    Anyway thanks for reading my Brooks TCG posts.

    Hello again Baron.
    Sorry if my writing is confusing. The shaft is 1 piece. Where it is welded to the end laminations the weld can be more than needed and at both ends the shaft is welded on the same side. This causes the shaft to bend and you will never get the wheel to run true without correcting it. Better grinders use a heavier shaft and have few problems. With the old Waldown and GMF grinders the 6" unit had a 3/4" shaft and the 8" a 1" shaft. One of my grinders is a Waldown brazed tool grinder, maybe 50 years old and runs very well.
    Good grinders make better tools.
    Regards
    BC

  9. #174
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Bernie,

    Sorry if my writing is confusing. The shaft is 1 piece. Where it is welded to the end laminations the weld can be more than needed and at both ends the shaft is welded on the same side. This causes the shaft to bend and you will never get the wheel to run true without correcting it
    I completely agree with you, I've also seen some induction motors that have been like that ! The result of some cheap sweatshop work.

    I've started to re-read my posts, on odd occasions I've found myself writing my thoughts way ahead of what I should ! Then when I read it back realise that it doesn't make sense. I've missed words out or a letter in odd places.

    I'm just going to blame it on old age and rubber fingers, though this keyboard is getting flaky as well as me
    Best Regards:
    Baron J.

  10. #175
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Thumbs up Wheel Hub !

    Hi Guys,

    I've had a play with the motor out of the tile cutter/saw, and have a new bearing for the gearbox output shaft which is 8 mm in diameter. I've also measured the shaft rotational speed at about 10K rpm on 240 volt mains.
    which is a bit fast for the grinding wheel. However I do have a 0 to 65 volts DC variable power supply capable of 5 amps. Putting the full 65 volts across the motor produces a nice 3.5K rpm, with the motor drawing 1/2 an amp no load. The motor body has a 70 by 62 mm cross section so is a manageable size, so I propose to use this motor and see how it fares in use.

    18-02-2020-012.jpg

    This motor is 142 mm long ignoring the output shaft which is 8 mm diameter and 32 mm long with an M8 thread on the end. Complete with the nut you can see in the picture.

    Grinding Wheel hub.png

    The existing plastic wheel hub is sized for a 22 mm wheel bore, so wouldn't be suitable for machining down to 20 mm to suit the aluminium hub of the grinding wheel.

    13-03-2016-013.jpg

    This is the sort of grinding wheel that I am proposing to use. Its a 100 mm diameter dished 180 grit diamond one. Chinese of course and about a quarter of the price that is wanted here. It has a maximum of 5K rpm.

    Now I'm going to go away and work out how I'm going to mount this motor. I'm hoping that I can persuade it to fit into a short length of 75 mm plastic water pipe. Not just from an electrical safety point of view but a dust one as well.

    Thanks for viewing guys.
    Best Regards:
    Baron J.

  11. #176
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Thumbs up Wheel Hub Made !

    Hi Guys,

    Today I've made the hub for the grinding wheel ! I used a 20 mm thick slice from a piece of 45 mm diameter EN16 bar, might have been 4140, either way it was tough stuff to machine. As you might be able to see from the poor finish. Anyway I faced off one side to get the 18 mm width using the lathe soft jaws to hold the workpiece. I didn't bother with a sloping face, since it would only be cosmetic anyway.

    23-02-2020-004.JPG23-02-2020-006.JPG 23-02-2020-005.JPG

    This is the hub. The bright rings are where I've undercut slightly to remove the curved fillet at the root of the collars. The hole was drilled 7.9 mm and reamed to 8 mm to fit the motor shaft. In the third picture you can see the saw marks from the bandsaw. I didn't bother facing off that side since it is within a couple of thou of parallel and doesn't touch anything.

    23-02-2020-003.JPG 23-02-2020-002.jpg

    A few pictures of the hub on the motor shaft and the hub with the grinding wheel fitted.

    23-02-2020-001.JPG 23-02-2020-007.jpg

    This is what happens when you drop the grinding wheel onto a tiled floor !
    I'll let you put your own expletives in here. Mine are unfit for publication.

    Otherwise it fits like the proverbial glove. Under test with the 65 volt DC power supply it runs smoothly and true. The motor is also a lot more quiet on DC than running it directly on 110 volts AC. I'm thinking about rectifying the AC, smoothing the output and using a triac to control the 240 volts AC into the 110 v transformer. Doing that would allow me to have speed control and reduce the noise that is produced when the motor is fed AC.

    I had hoped that I might be able to fit the motor into a piece of 75 mm ID plastic drain pipe. No such luck, the brush holders need an 80 mm bore to fit in. I tried squashing the pipe I had, a bit but the spring back pressure would damage the plastic housing, so no go.

    That is as far as I've got for the moment.
    Thanks to Familyguy for putting me onto the tile cutter motor.

    Thanks for looking.
    Best Regards:
    Baron J.

  12. #177
    Join Date
    Dec 2007
    Location
    Adelaide
    Posts
    574

    Default

    With regards to the motor I was thinking more of an induction type motor, the motor I saw on a tile cutter at the boot sale was an induction motor - the switch gear/power cord etc was part of the motor housing and fully sealed against water so it would probably keep out dust as well. It looks like you have done ok with the ac/dc motor so far, it will be interesting to see if has enough grunt at 65 volts. I recall seeing a diy tool and cutter grinder on youtube that used an angle grinder so it is not the first time this type of motor has been used. Pity about the wheel.

  13. #178
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi FamilyGuy,

    Pity about the wheel.
    Yes, I had it in my hand one second, the next it was on the floor ! I guess I must have twitched or something.
    At least I didn't pay UK prices for it.
    Best Regards:
    Baron J.

  14. #179
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,541

    Default

    Quote Originally Posted by BaronJ View Post
    ...I had hoped that I might be able to fit the motor into a piece of 75 mm ID plastic drain pipe. No such luck, the brush holders need an 80 mm bore to fit in...
    I think you would be better off with a piece of metal pipe or tube. I would not like to use PVC in case it started to soften and move a bit.

    Michael

  15. #180
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Michael,

    I've not had any luck finding either a die cast box or some metal tube that I can press into service as a container for the motor.

    One of the issues is going to be the cooling ! There is a fan on the front of the motor which is designed to pull air from the rear end through the windings and out of the front. If you noticed in one of the pictures, post 167, there is an orange plate which fits across the motor body just behind the fan. That plate is an air baffle designed to prevent air from just being circulated around the outside of the motor.

    However I enclose the motor, I am going to have to replicate that baffle somehow ! Leaving the motor open is not an option in this case, particularly if I am going to slow it down.
    Best Regards:
    Baron J.

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