View Full Version : Q : What is "blanchard grinding"
06-30-2005, 09:41 AM
Maybe it's a dumb question but can someone tell me what is meant by blanchard ground (as in a 12" X 12" blanchard ground plate) ?
06-30-2005, 09:46 AM
Like a surface grinder except it has a vertical axis spindle. Usually very big machines.
[This message has been edited by BillH (edited 06-30-2005).]
06-30-2005, 09:59 AM
06-30-2005, 09:59 AM
06-30-2005, 10:11 AM
Known as blanchard grinders in the US as they are made by Blanchard.
Known as Lumsden grinders in the UK as again this is the UK maker.
No difference, same operation.
06-30-2005, 12:10 PM
Phew! I thought that the dreaded aluminium pans had got me. Lumsden- Gateshead- not there any more- we were shareholders- once did a Myford up on one.
Are there any left- for a ten minute job in the North of England somewhere?
Have lathe bed, will travel.
06-30-2005, 01:07 PM
I ran a blanchard at Vickers Omaha plant, easy job,vane pump rotors had to be +/-.00003
06-30-2005, 02:56 PM
I have always heard that Blanchard grinding could produce the flattest surface. Had a customer bring me several plates to surface grind on one side. (6 x 18 surface grinder) Gave me fits until I realized that the Blanchard ground side had a concave to it. I know the grinding head tilts from side to side. How do you know when it is flat? Thanks
07-01-2005, 12:47 AM
Chief Mcgee,we used them in optics Fab, in the last Century. You test the flatness of the work with a spherometer, to measure the depth. You can also give the piece a fast "polish" to use an optical flat or interferometer. The real Blanchard grinders were for flat work, but folks seamed to refer to any "generator" as a Blanchard. My boss once said they would hold a few fringes from flat (1 fringe is .000025inch) from flat
07-01-2005, 01:29 AM
Thanks for all the replies - much appreciated...
07-01-2005, 05:09 AM
An old guy told me they were a big thing that took the shapers out of american industry , shapers were used a lot for squairing and descaling die steel chunks prior to starting machining on them . Apperantly they work to equalize the stone wear by rotating the workpiece slowly as the grinding head spins ?
07-01-2005, 12:01 PM
A Blanchard grinder is a great machine.
The link posted for the 300 inch machine is not a good representation of the average Blanchard. The most popular sizes seem to be from 36" tables to 96" or so.
A Blanchard has a vertical spindle with a horizontal wheel. The circular table or chuck rotates CCW while the spindle turns clockwise.
On mine, the spindle only has one speed while the chuck has four speeds with the highest being 64 RPM. My model is a No. 11-16 which translates to an 11" wheel with a 16" chuck which will actually swing an item about 20" diameter. It is 15 HP on the spindle. Max downfeed is .070 IPM.
It is a perfect machine for making and sharpening my punch and dies. You do have to tram in the spindle for it to grind flat, depending on the size of the work. The Blanchard leaves a distincive crosshatch pattern of grinding marks on the work.
In addition to using the 11" diameter AO cylinder wheels, I also have a diamond wheel and wire brush wheel. The larger machines typically use segments rather than full wheels. I have seen 36" machines that use cylinder wheels. The wheels aren't cheap. Ones for mine cost $150 each but last a long time depending on use. My current wheel has been on the machine for 18 months. That is a non-production setting though.
Just Google on Blanchard grinder or do an ebay search and you will see a wide variety of machines.
Hope this helps answer your question.