Disc Grinder Advantages

izafireman

Well-Known Member
Following on from the post by the Boss regarding disc grinder plates and the bonding of papers to the surface plate of one I have been looking into making one as I am in the UK and to buy a US model/shipping would be hugely expensive.

So, what I am looking to do is buy the hub/plates from the US from Rod Nielson and then obtain a good motor over here along with VFD controller and get one built for me, maybe even do the job myself.

What I would like to know from the guys that use them what are the advantages, or if any disadvantages and any tips when using them, do I need a table etc.?

I would imagine the main use for mine,if I do this would be for sanding down stabilised wood as a the moment using pre bought tacky backed papers its costly due to the price of the papers.

Am I also correct that they are very good for flattening both scales and blanks?...…the disc sander I have at present certainly isn't good for this as it has one speed which is fast! and so it just grabs materials.

I believe some also grind knives out on them too as opposed a belted machine?

So any advice welcome or tips.

Many thanks.
 

Gliden07

Well-Known Member
Check out this video by Nick Wheeler:


This should explain everything you would want to know about disk grinders.
 

timgunn

Well-Known Member
Be aware that an imported "standard" US one will not fit a metric motor shaft (IEC frame standards). The US tends to use NEMA motors and the Nielsen hubs fit 5/8" shafts.

NEMA motors are typically 3 to 4 times the price of similarly-rated IEC motors in the UK.

It's not particularly difficult to bore one out to fit, but the machinery needed to do it is the same as that needed to make one in the first place.
 

izafireman

Well-Known Member
Be aware that an imported "standard" US one will not fit a metric motor shaft (IEC frame standards). The US tends to use NEMA motors and the Nielsen hubs fit 5/8" shafts.

NEMA motors are typically 3 to 4 times the price of similarly-rated IEC motors in the UK.

It's not particularly difficult to bore one out to fit, but the machinery needed to do it is the same as that needed to make one in the first place.

Thanks for the reply Tim.

What I was intending doing was getting the hub/plates from the states and the motor from here in the UK.

But before I did anything I was going to let an engineering pal look at everything first as I thought there might be an issue with bore sizes.

Knowing him he might even just make me the hubs and the plates to fit as although I scratch my head at stuff like this to him its a doddle.

Thanks for letting me know.
 

Sean Jones

Well-Known Member
Thanks for the reply Tim.

What I was intending doing was getting the hub/plates from the states and the motor from here in the UK.

But before I did anything I was going to let an engineering pal look at everything first as I thought there might be an issue with bore sizes.

Knowing him he might even just make me the hubs and the plates to fit as although I scratch my head at stuff like this to him its a doddle.

Thanks for letting me know.
If your engineering friend has a lathe there are two ways to accomplish a fit. If the shaft on your motor is larger than the bore on the plate it's relatively easy to either turn down the shaft or enlarge the bore. However if the bore is larger than the shaft then he'll have to make some kind of a sleeve. That would be a lot more work. Something to consider when you look for a motor.
 

izafireman

Well-Known Member
If your engineering friend has a lathe there are two ways to accomplish a fit. If the shaft on your motor is larger than the bore on the plate it's relatively easy to either turn down the shaft or enlarge the bore. However if the bore is larger than the shaft then he'll have to make some kind of a sleeve. That would be a lot more work. Something to consider when you look for a motor.
Yes, he is actually doing the same for my buffer as that needs sleeves making for the 'pig tails'

Thanks
 

izafireman

Well-Known Member
Ok ....I have made some progress after phoning a company and speaking to a guy there who asked me what Horse power I needed, I said I would imagine 3/4 min, possibly 1HP......would you guys agree?

He said as its the UK I need a three phase motor, 4 pole, the VFD would convert the single phase fee to 3 phase.
The motor will have a 19MM key way hub.

But he said what RPM would I need...….this I don't know, what would anyone suggest please?

This would all be controlled by a VFD.

Thanks in advance.
 

KenH

Well-Known Member
Agreed 3/4hp is plenty for a disk grinder, could even "get by" just fine with 1/2 hp. This is one place I like 1800 RPM over the 3600 rpm motors, but with VFD motor rpm isn't very critical as you'll control from 200 rpm to max, and very little max RPM will be used with Disk Grinder. OR - that's my experience anyway. I don't grind bevels, other than touching up to clean up grind lines and smooth things out.
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
Staff member
All this.
Agreed 3/4hp is plenty for a disk grinder, could even "get by" just fine with 1/2 hp. This is one place I like 1800 RPM over the 3600 rpm motors, but with VFD motor rpm isn't very critical as you'll control from 200 rpm to max, and very little max RPM will be used with Disk Grinder. OR - that's my experience anyway. I don't grind bevels, other than touching up to clean up grind lines and smooth things out.
 

izafireman

Well-Known Member
Thanks for the replies guys as I don't want to buy something and then realise its not really any use months down the line as such.

I just contacted a couple of suppliers , one sent me a link to a motor plus a speed controller but the other supplier sent me the image of what he has just made for someone but for another application. I said its a maybe.....if he can make the box smaller and ensure its dust/water spray rated and the correct speeds etc.

Cheers P
 

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