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View Full Version : BillH: 7x12 spindle runout.



pgmrdan
11-15-2004, 09:29 PM
BillH,

You mentioned in another post that I should check the runout on the inside of the spindle of my Grizzly 7x12 mini-lathe. I just did and it came out to .0005" TIR or perhaps a hair less.

I used one of my Starrett Last Word indicators so it should be just about right.

Again, I think I may have gotten a fairly good one based upon this and some other measurements I've taken. I think yours came out to about double what I got and that had you concerned.

Did you ever think of running a MT3 reamer in the spindle if you thinks it's too far out of line? (Personally, I wouldn't bother since a 4 jaw independent chuck can adjust that out but it'll still be there when you use a center.)


Anyone,

On one of my Last Word indicators the rubber boot is missing. Can I get one of these somewhere without sending in the unit for repairs?

Thanks,
Dan

JCHannum
11-15-2004, 09:43 PM
Rubber boot??? None of the Last Word indicators I have ever seen have a rubber boot.

pgmrdan
11-15-2004, 10:06 PM
They are both Starrett No. 711 indicators. One has a boot (my name for it) and the other doesn't. I assume it should too.

On the Starrett website it looks like it's listed under attachments for the No. 711.

Rubber Dust Guard N PT09764 71290

Must be an option. Maybe only one of mine came with it originally. Nice option.

[This message has been edited by pgmrdan (edited 11-15-2004).]

nheng
11-15-2004, 10:45 PM
Dan,
Keep in mind that when using a center in the spindle it can be softer and can be cut in place (or ground if hard). The runout then is pretty close to zero limited only by bearing class and condition. Also, if the lathe can take a collet and driver plate at the same time, any piece of rod can be cut as a near perfect center.
Den

BillH
11-15-2004, 10:56 PM
Its better than mine for sure, but again mine is only about .0005 more off.
I have 2 cheap chinese dial indicators, and using them enough I find the accuracy is about .001 because as the rod flexes, the indicator needle bounces around from friction on the tip.
I used a dial test indicator on my spindle, has .0005 resolution, cost me 40$, so a little nicer than the dirt cheap stuff.
My 7x14 is sitting on a wheelie on the floor, I have no table space for it. If I did, I would use it for some stuff, namely threading, since I dont have change gears for my sb.

pgmrdan
11-16-2004, 09:29 AM
Den,

If I need something more precise I can, as you suggest, turn the center or adjust the 4-jaw independent chuck I almost always use. Right now it's plenty close for the work (play?) I do so I'm not going to worry about it.

*****

I'm very pleased that my lathe is working out as well as it is after seeing how many negative comments are made about the Chinese mini-lathes.

And as little time as I have to use it I'm glad I went this route instead of buying a used lathe that needed to be restored first.

Mine isn't perfect but it's very useable. (Replacement parts are plentiful and cheap. There are several user groups where people can get help specific to these lathes. Lots of projects and articles written up for micro-machining including Rudy Kouhoupt's Shop Wisdom books.)

[This message has been edited by pgmrdan (edited 11-16-2004).]

BillH
11-16-2004, 11:39 AM
When I was at the HF store, I took a look at their 9x20 lathe. It occured to me how it really does look like a scaled up 7" lathe, compared to the south bend I have.
Mainly, the width of the bed is pretty narrow compared to old american iron, and the crosslide dove tails are close together for no apparent reason.
I also noticed though that the el cheapo 3 in 1 machine had some surfaces hand scraped, go figure.
THe negative feedback on the mini lathe will always hold true if you push the lathe beyond it's limits. But again, thats true for any machine tool.

Rex
11-16-2004, 02:14 PM
Comparing my $350 Logan 9x17 to a new HF 9x20, I lucked into a good deal despite my ignorance.