Motor Advice Please UK

[bernie]

I'm looking for a suitable grinder motor in the UK. Generally they are AC, 240v @50hz and they run 1500 or 3000rpm, it will be 2hp High Torque, Capacitor Start. I will be using 2 Maska 3 step pulleys, one on the grinder and one for the motor.2"3"4" setup would give me approx' 3000,1500,750rpm.
So which one would be the best, 1500rpm or 3000rpm and what size pulleys would I need to get the speeds required. I've asked Rob this one also and i'm sure the Guru will come up with the answer or know a man who does. An answer from a UK perspective would be helpful.

Bernie :confused:

[Colin KC]

Hi Bernie,
Have you asked that fella from the grinder company that you posted?

Where have you got your supplies from, how about posting your design?

It sounds as if you'll get your 3000, 1500, 750, with the 1500rpm motor, but twice that with the 3000 one.

Still, I know very little, just here for moral support & biscuits (& to squeeze you for information of course

[Rob Frink]

Bernie,

The solution is a simple one. I recommend that you use the 1500 rpm motor. Then to make up the speed loss from the 1725 rpm design here in the States, I can supply a larger drive wheel on the grinder. The standard wheel is 4" diameter..... to make up the difference, we can use a 5" diameter or so.

Grinding speeds are mostly personal preference, where I've found that it varies as much as the makers thenselves. You may not notice much difference anyway. It is something that you quickly become adapted to. Folks that started with a fast grinder, inherently are more comfortatble grinding on the fast side....and visa-versa. I think I like the slower end of the spectrum to keep me in check in case I make a mistake. For reckless material removal, you can run as fast as you like with industrial machines as fast as 8000 ft/min .....but for grinding the bevels on blades....I do this about 1000-2000 ft/min with 80 grit. Just my personal preference.

The draw back with the 3000 rpm motor, is that it may not be as convienient to slow the grinder way down for finishing speeds...say 500-1000 ft/min range.... It can surely be done but requires a great difference in pulley sizes from the motor to the grinder such that the motor needs to be movavble to adjust the drive belt tension for each speed choice.


With a pair of 4",3",2" step pulleys, the distance from the motor shaft to the grinder shaft is nearly constant for each belt position, such that the motor doesn't need to be moved when you change the belt position. You can simply roll the belt out of one groove, into the next smaller groove like changing speeds on a 10 speed bicycle. This is why I like the lower RPM motor with this size step pulley.


Just some food for thought. It sounds like you are aready one the right track though.

Take care,
Rob

[Martyn]

Rob, I posted this somewhere else, but I think it got burried. Just a thought, I've admired your KMG1 for some time, but I'm a very amateur knifemaker and could barely justify the expense, but possibly. The real killer is that I am in the UK. I dont know how heavy the KMG1 is, but I'm betting shipping costs would put a couple of hundered US$ onto the cost. Then we have tax at 17.5% and import duty too, which would take your basic model cost from around $800, to about $1300 for me. That's just too much. Do you think it would be possible to produce a cut down version for export, like the hard to manufacture parts only, maybe the tensioner/alighnment assembly and platten, maybe the drive pulley and pillowblock bearings, dependant on weight/cost? It would make life much easier for me, I could probably fabricate the rest from wood or MDF. I would loose functionality, obviously, but would have the bare necessary for a quality grinder? Maybe you could offer a modular system, so that people could buy the fram or tool arm later, to upgrade to the full KMG1 system.

What do you think? I know there are at least a couple of UK knifemakers who are looking to buy, but are put off the KMG by the huge import duty/tax/shipping $$$ hit in the pocket. I'm sure if you got some basic parts out to people, they would probably upgrade over time and you would add to your customer base.

Cheers,
Martyn.

[Rob Frink]

Martyn,

Thank you for the suggestion. I have some...but limited experience with international KMG1 shipments. It seems that the taxes and tarriffs are really a killer and they vary dramitically from country to country.

On many occasions, I've sold just KMG1 components for folks that are building their own machines. Feel free to shoot me an email with your requirements and I'll gladly put some kind of "package" together for you.

Great thinking...thank you!

Rob

[Martyn]

Originally posted by Rob Frink


On many occasions, I've sold just KMG1 components for folks that are building their own machines. Feel free to shoot me an email with your requirements and I'll gladly put some kind of "package" together for you.

That's great Rob, Thanks. I'ts great to know that there is such flexibility in your product and such a willingness to help the community.

I'll check over what I think I need and doubtless will drop you a line.

Thanks,
Martyn.

[bernie]

Hi Colin,
I've decided on Rob's KMG-8 with a modified platen, Ed Caffrey's to blame at least thats what i've told the misses.
The appraisals from some of the top guys in the business made my choice easy in the end.
101 reasons why I chose not Homebuild and funny thing is cost was one of them, i've yet to get a press drill and I know the one you guys use and available from Machine Mart is adequate for 99% of my needs, but if i'd gone for Homebuild I would need the much bigger one to cope with the drilling required, overkill for most of our needs ?. Made a number of enquirys for balanced pulleys,seems their cast and machined but not balanced approx ?26, Maska pulley balanced approx $34 = ?21 got duty I know and delivery cost but get my point. I'd of also gone with Rob's superb wheels anyway even on a Homebuild ?.
You musta seen Mike Conner's "Here's The Grinder" quoted ?110 for ally cut to size, that would've been my goal. " MAGIC "
Rob's a great guy to deal with and will help in any way he can.
His choice of shipping agent has a great network established here in the uk. Several options available,Collect from airport of your choices, clear custom and pay duty yourself or Have shipping agent clear customs and deliver to your door. Base package approx 130lb, delivered to just airport of choice approx ?105 at current exchange rate + your duty. I hope Martyn sees this, nowhere near as bad as I anticipated, UPS to blame.
? for ? Rob's rig is easily the best available and appraisals to date bear testament to this.
Bernie

[Colin KC]

...Gonna hijack your thread here, a little bit.

Rob, I have a motor, it's old & has no plate anymore, but it does work, any ideas on how to work out it's RPM?

Also, here's an idea for a grinder, please chip in anyone on suggestions/criticism e.g. will the bottom mounted tensioner lead to chatter/bounce?

[IMG]C:\My Documents\BELTSANDER.bmp[/IMG]

Will probably add provision for a vertical platten, i.e. another idle wheel directly below contact wheel.

[Colin KC]

Stoopid *%&$??"@^$%??%^%^^&&^ING computer type stuff, type thing

[bernie]

Can I have some of that mate.

[Colin KC]

Bernie, sounds good, but , & this is for you too Rob, & probably not as much of a problem as I think, but how do you get a horizontal platten with a top tensioner?

[bernie]

I'm still on Leggo, Rob can have that one.

[Bladewayze]

Hi Bernie,

I don't yet have a lot of exprience with blade grinding as such, but I do use a multi-speed woodwork lathe. I can tell you that the size of pulley-wheels required, to obtain any set speed will depend on the diameter of the pulley wheel on your motor shaft.

A basic example:
A motor-shaft pulley twice the diameter of the grinder pulley, will double the motor output speed at the wheel. Conversley, a motor-shaft pulley that is half the diameter of the grinder pulley, will reduce the speed by half. I am sure you will be able to calculate the sizes of pulleys you need from that.

Happy Grinding Bernie
Bladewayze in West Mids

[bernie]

Hi Bladewayze,
Welcome and thanks for the input, as a Newbieee! I'm easily Humbled, but theres so much inspiration around at the touch of a key, you can get advice from some of the best Knifemakers around. They've been there done it and got the t-shirt. Hammer that search button lots of great stuff in archives.

Have fun Bernie

[Rob Frink]

Colin,

I don't understand your questions...but I'll take a shot at them....If you need more explaination or if I missed the boat...let me know we will try it again.

this is for you too Rob, & probably not as much of a problem as I think, but how do you get a horizontal platten with a top tensioner?

I'm not sure what you mean. But here is a concept to think about. You want the tensioner/tracking device to be on the "low tension" side when the machine is working. For example, When you grind very heavy with a high load, the abrasive belt tension increases in between the drive wheel and the contact wheel. This is simply from the motor force puling the abrasive belt to keep it spinning. The harder you grind, the more resistant you put on the abrasive belt to stop turning...then the more the motor needs to pull to keep it going. On the KMG1, this is the lower section of belt from the contact wheel to the drive wheel. If the tensioner is placed in this area, then the tensioner would simply colapse under grinding loads and the belt would become loose on the top rollers and fall off. This can be seen if you run the KMG1 backwards. It can be hazardous.

I hope this makes sense...if not let me know and I'll try to explain better.

Rob, I have a motor, it's old & has no plate anymore, but it does work, any ideas on how to work out it's RPM?

Not sure....you can do the "smoke test".....plug it in and see what happens. If it runs, try to campare it to different motor with a known speed. The hazard here is that without the name plate, you probably don't know the motor voltage either i.e. 110v or 220V ...so you run the risk of damaging the motor with the wrong voltage. I'm afraid I can't help you here...sorry. Maybe a local motor shop can help..?

Take care'
Rob