Surface Grinder info?

[infinitreeservices]

I need a surface grinder to resharpen woodchipper blades.
I hope someone might be able to point me in the right direction...
They are up to 20cm long 7mm thick,obviously they need to be kept cool.The angle needs to be exact, 42degrees for example.
Ground on a hollow grind disk in a smooth horizontal motion.
Would a jones and shipman machine be suffice?What model/modifications etc?Budget of £1000
Apologies for my ignorance..Any help would be much appreciated

Attached is the closest machine I'v found but runs at £8k

 

[ornerynorsk]

Does the blade need to be hollow ground? There are machines available that would be more appropriate and more conducive to the type of grinding for your application. You could hollow grind an edge on a surface grinder, but it's not the most convenient way to do it, as all of your work is being performed on the Y axis, which means an enormous amount of labor for the operator if more than just 1 or 2 passes are required.

 

[unclesyd]

I would look around for a small tool room grinder that would accommodate your blades. You could find these either reconditioned or rebuilt on the surplus market for very reasonable prices. The only problem I see is that you may have to have to make a fixture to hold your blades.

http://compare.ebay.com/like/180573...fc201a9&itemid=180573153222&ff4=263602_304662

 

[infinitreeservices]

Thanks for the replys chaps-
ornerynorsk- A valid point but no they aren't to be hollow ground-Hollow grinding does cut better but it won't keep its edge for as long..
Will that make any difference as to machine choice?

unclesyd-I was thinking about making a complete jig around a bench grinder,but that may take a while...

 

[ornerynorsk]

Yes that does make a tremendous difference. Making a simple angle fixture to hold your blade and then grinding in the conventional fashion on a surface grinder will be very easy.

As to the model/size/type of the machine, drop into a machinery dealer and see what's available to your locality. You'll want one with coolant, as you mentioned in your original posting.

 

[saberblue]

If the hollow grind cuts better you might want to buy a machine capable of doing both the hollow grind and the conventional grind and then look at different materials for the blades --- used to make similar blades out of Tantung G and Carbide and they lasted a very long time - but as in most things IAD rules (it all depends)

the direction that the grinding marks lay on the finished piece will make a substantial difference in how long the knives stay sharp -- if you "burn" the knives you will really kill you tool life

Good luck it sounds like and "interesting" project

A.R. "Andy" Nelson
Engineering Consultant
anelson@arnengineering.com