Thought you guys might like these pics and some impressions of this spindle. Some background... I have been lurking eBay for years looking for a Gilman or similar box spindle in this size. As I mentioned in another thread, I finally scored one. This is only the second 2750 box spindle I've seen on eBay. Gilman Spindles is now owned by SKF, and this particular sized spindle is just about perfect for a serious bench CNC mill or perhaps for retrofitting just about ANY square-columned or similar mill-drill sized machine.
My first impression - bigger and heavier than I anticipated. The spidle box is cast iron, and measures roughly 7" long by 2.5" square through the body section. Overall length is about 1 foot; weight 25 pounds. The body has counterbored holes, 4 ea, for 5/16" or 8mm SHCS. Bearings are ABEC 7 angular contact.
First picture: Overall spindle.
Second: Spindle nose. The collet nose reminds me of basically a big and beefy ER collet type of setup. Max collet capacity is 0.750". The fit and finish is everything I expected from a quality unit. This particular example uses a 75TG collet system, and these are common and available from companies like MSC. I'd rather have a CAT30, but collets are pretty user-friendly, and since I can add a drawbar, I could always create fixed tooling using holders with the 75TG taper, and a drive-dog which would replace the current collet nut.
Third: I mounted the spindle in my 6" Kurt vise and checked the runout with my best B&S 0.0001" indicator. When smoothly rotated, I can detect no needle motion on the internal taper. A carbide end mill was mounted; the first test scared me a bit because it showed 0.001" on the cutter shaft, but I had only tightened it by hand. When correctly wrench tightened, the runout was 0.0001". A true pin guage would be more appropriate for this test than an end mill, but carbide end mills are pretty accurate.
Fourth: This shows the relative size. The little spindle on the left is an ER16 cartridge spindle, roughly what you can call a Sherline size.
This is a nice unit! It is going to require at least 1 HP, and would probably be happier with 2 HP or so. Until I can decode the product number, I'm not sure of some of the other specs, but the top RPM should be around 7-10K, maybe up to 15-18K depending upon the bearing preload. Now I need to build a mill around this bad boy! I think I am going to try to replicate one of the CMS semi-gantry style of mill...
http://www.cmscnc.com/index.cfm?fuse...=100&pageid=40
It'll be a fun, long-term project. This time, I'm going to shoot for far more cast iron than my previous effort, which was 80% aluminum.
I know any clown can buy a spindle... the shop-made spindles we've seen in this forum are much more impressive. I really simply wanted to share my impressions, which are very positive so far.