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2009-09-22 18:47




  New Spindle





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CNC - BT30 Spindle - Shaft

With the housing done I decided to tackle what was coming to be the most problematic part of the whole project. When I'm writing this I still don't know if it will work or not.

I decided that I wanted the spindle shaft hardened and ground, at least the lower part with the taper and after discussing it with a local company they supplied me with a piece of SS2511 round bar.




Unfortunatly I didn't snap any photos while machining the shaft but here's two I took fresh off the lathe:

The main diameter of the shaft is 30mm and it is 240mm long. There's a M32X1.5 thread that will be used to lock the bearings in place.





This photo shows the setup I did to machine the slots and mounting holes for the drivedogs. First I made a collet kind-if-thing that fits the 30mm OD of the shaft. Then I used two Vee-blocks in the vice to clamp it.





Using a 10mm endmill I then machined the slots.







And here's the finished shaft before sending it out for hardening and grinding. You can see the "collet" I mentioned just above the threaded part of the shaft.





So now comes the problem. The company that does the hardening and grinding for me told me to leave 0.4mm on the surfaces I wanted them to grind - and I did. But since I shouldn't harden OR grind the upper part of the shaft I machined that to it's final dimension. (30mm). This didn't turn out well because the shaft got oval from the heat of the hardening and now there wasn not enough material to machine it back to being round. I should ofcorse have realised this was going to happen  but I didn't and I was now facing making a new shaft - something I did NOT look forward to. But then someone at a online forum suggested to have the shaft plated to build up enough material so it once again could be machined round and to the right dimension and I got hold of a nice guy that promised to help me with it.


And here it is. You can see the newly applied metal at the top. I was kind of expecting to see a nice shiny surface but this is what it looked like. I chucked it up in the lathe and took a light cut. The material was quite hard and left a nice surface. I then brought the shaft back to the grinding shop for a second time. As of today (2007-09-22) I haven't got it back. We'll see how it works out.




Update 2007-09-29:

I got the spindleshaft back from the grindingshop. They did a good job:


The shaft looks very nice. The surface on the taper is a little rougher than on the outside but still very nice. The dimensions are exactly as I expected - no more, no less. I'm happy.










Copyright 2009 Henrik Olsson. All Rights Reserved.
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