DIY surface grinder

[satx]

So many great ideas, thanks

Using the mill as base for surface grinding, wonderful, economical double-usage for small shop area.

Put the magnets behind aluminum plate, 3 mm plate?, with a lever to pry the magnets away from the alu plate so the steel dust drops away.

[JoeH]

great post. I look forward to the videos especially any that show how the magnets are used.

[Ralphxyz]

I mounted a cup wheel directly to the spindle once (horizontal). Worked great, now I need to find some good magnets or make an electro-magnet.

Ralph

[tonyfoale]

I mounted a cup wheel directly to the spindle once (horizontal). Worked great, now I need to find some good magnets or make an electro-magnet.

Ralph

I put a wheel directly on the spindle also for a specific cam making application.

Click for full size.

[Ralphxyz]

I wonder what the disadvantage/dangers are to using the wheel directly on the spindle.
One advantage I saw was it really highlighted how much my tram was off.

Ralph

[tonyfoale]

I wonder what the disadvantage/dangers are to using the wheel directly on the spindle.
One advantage I saw was it really highlighted how much my tram was off.

Ralph

Ralph,

It depends why you mount a wheel directly to the spindle. In your case it sounds like you were using a cupped wheel for blanchard surface grinding. that generally puts more load on the wheel than conventional surface grinding.
I my case I used a flat wheel, grinding on the periphery in effect like a normal cylindrical grinder stood on end. I did this to be able to use the CNC features of my mill to grind an irregular profile.

Dangers are like any grinding, wheel explosion is the worst. Strong covers are good if they do not interfere with the required work. If wheel covers are not possible then a barrier between the wheel and operator is well advised.

[marksbug]

I wish I had a tenth of the energy & ambition & drive tony has. I seem to be slowing down faster than I ever though possible, kinda like a jet fighter landing on a aircraft carrier. keep it up tony I still love looking at your work!!

[tonyfoale]

Some updates on this.
When used as a "tool post" grinder (more like a cross-slide grinder, because it is solidly bolted to the cross slide) the finish was not quite as good as I thought possible. I swapped out the grinding spindle for one made from a heavy cast iron housing. This made a big difference. Here is a photo with it on the lathe and another showing the strong steel wheel guard.

click images for full size.

This is a view of some grinding tests, greatly magnified with a digital microscope, I forget the actual magnification. On the right of the first photo is the finish obtained with the previous spindle and on the left with the current version. For comparison the photo on the right is of the finish on a quality 5C collet.



I also found an electro-magnetic flat chuck on the usual auction site at a cheap price. The seller said that he tested it and it did not work too well. His test power was AC and DC is necessary so I took a chance that the chuck was OK but the test method was not. I was right, it works fine. It was also rusted all over but it cleaned up easily.




As for surface grinding on the mill that will be made obsolete by a new project, which unfortunately had to be put on the back burner for a few months due to other more pressing tasks. The new project is a dedicated high precision CNC surface grinder. The table will move on linear ball slides and be driven by closed loop steppers controlled by my dedicated software. To test certain features prior to cutting metal I cut wood instead and mocked up the table and drive system to test whether the stepper size that I calculated would be capable of throwing the table and mag-chuck about at the usual surface grinding feeds. I used a 20 mm pitch ball screw to get the speed. I'll make the base of this grinder in epoxy/Granite and I have a piece of solid granite of suitable size to make the table from. I'll make a full post on this when it is finished, I will be getting back to it later this coming week. In the meantime here are some pix of the wooden version which passed all the tests.

[tonyfoale]

I wish I had a tenth of the energy & ambition & drive tony has. I seem to be slowing down faster than I ever though possible, kinda like a jet fighter landing on a aircraft carrier. keep it up tony I still love looking at your work!!

I have the drive but I am 80 in two days so the energy is draining rapidly. I expect that it will have deserted me within the 20 years that I intend to have left. There are a lot more races to ride yet.

[marksbug]

yes big shaft&support are importaint as is "tight gibs" along with balanced wheel. some cam grinders have gone to diamond wheels that locate much tighter and grind almost as smooth as glass. there very impressive especialy when they do the tool steel camshafts. I believe they still rough in with stones on most applications then go to another machine for finishing or heat treating first.