Thread: Radius Dresser

Thank you for your interest in Crush Dressing of Grinding Wheels.
Firstly let me explain this was a method I learnt 50 or so years ago in a Toolmaking Apprenticeship. I learnt the technique from an experienced Toolroom Surface Grinding person whos full time job was operating a Churchill Surface Grinder.
This bloke had a lot of knowledge years of experience & the methods he used worked.
So its been a bit of a challenge to recall everything learnt at that time.
Here we go...
Firstly this method works effectively on Vitrified Grinding Wheels on Surface Grinding Machines.
The Photos explain the method used.
The holder with a .250" dowel axle, was made by me at that time.
The crushing roller is machined as a mirror reverse of the profile required, for one off jobs it could be left in the unhardened condition. Multiple jobs could require hardening of the roller. The roller is 1 1/4" Dia. with a reamed .251" centre hole concentric with the OD.
The crushing roller set up is clamped on the grinding wheel centreline & held by the magnetic chuck.
The grinding wheel is rotated by hand using a suitable crank handle,& at the same time the wheel is fed down onto the crushing roll at a rate not exceeding one thou (.001") per revolution, so as not to overload the wheel & spindle.
Critical work like Toolroom grinding then required a razor blade to be set up in a small vise & a trial cut taken by the wheel.
The razor blade was then set up on an Optical Comparator to check against a master or an enlarged drawing.
I checked on Google & this method is still in use in some places. One bloke had succesfully ground some gear teeth using a wheel formed in this manner.
The crushing method leaves a free cutting grinding wheel.
Hope this may be of interest.
regards
Bruce
ps regarding safety, suggest that the power to the machine is disconnected, so that no start switches are accidentally bumped during the process.
Guards on the grinding wheel should be refitted before power start up of the machine is made after crushing operations.