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Gallery, Projects and General => The Design Shop => Topic started by: vtsteam on June 16, 2015, 02:22:21 PM

Title: Question: Split bearing housing for roller bearings?
Post by: vtsteam on June 16, 2015, 02:22:21 PM
Thinking about the headstock casting design for my new lathe, I was wondering if it would be inadvisable to split the spindle's roller bearing housing (ie base and caps)  assuming sufficient material thickness and support otherwise.

I'm familiar with splitting the bearing housing for sleeve bearings, but I was wondering if it is ever done for tapered roller bearings? Not experienced with these.

It  would be nice to be able to remove the spindle assembly without having to use a puller. It would also mean I could do the casting in two parts, and more easily fit a heavy casting pour in the crucible capacity I have.

I know bearing preload will add some stress to a bolted housing, but I can make the base cap and bolts quite stout and well supported in that area. Shims can adjust a slight radial pressure on the bearing assuming a close bore to start with.

Anyway, thoughts?
Title: Re: Question: Split bearing housing for roller bearings?
Post by: awemawson on June 16, 2015, 02:36:32 PM
If the casting / housing is split, and the mating faces are true, then so long as they are dowelled together and then bolted together normal pre-load can still be applied I would have thought.

Are you planning gears within your headstock Steve ?
Title: Re: Question: Split bearing housing for roller bearings?
Post by: vtsteam on June 16, 2015, 02:57:27 PM
No drive or back gears planned at this point, Andrew. The Gingery didn't have any either, though they can be added later as a mod.
Title: Re: Question: Split bearing housing for roller bearings?
Post by: vtsteam on June 16, 2015, 03:25:51 PM
Another helpful aspect if I can split it is that I can probably use the same boring bar and setting to bore both bearing recesses at front and back without changing anything. Each recess has an inside lip, and the boring bar can't make it through that, but if the cap was removed the tool bit could face up, slide through to the other side, and then replace the cap, and bore the other recess.

I would definitely prefer to do it that way than remove the boring bar from the boring jig setup, or move the tool bit in and out to cut both recesses.
Title: Re: Question: Split bearing housing for roller bearings?
Post by: John Rudd on June 16, 2015, 03:35:34 PM
VT,
Where I worked before I retired, we had some big fans on fans fired heaters that had split bearing housings as you describe ....these bearings were quite large....4-5 inches diameter, the fans running at about 3000 rpm or so.....

I thought your idea would fine...
Title: Re: Question: Split bearing housing for roller bearings?
Post by: PekkaNF on June 16, 2015, 04:32:06 PM
How about cartridge spindle design and brackets against the shoulder?

This has many good features, like bushing that preloads bearings is long etc.
http://smg.photobucket.com/user/robwell/media/BardenSpindleDrawing.jpg.html

I'm not too thrilled boring recess on far end either. There are some work arounds. Like two different size bearings. Recess only for front bearing. Or bushing between bearings.

Pekka
Title: Re: Question: Split bearing housing for roller bearings?
Post by: vtsteam on June 16, 2015, 09:48:26 PM
Thanks Andrew, John, Pekka  :beer:.

Pekka the bearings and spindle are already in hand -- 7"x14" sieg lathe spindle, and two 30206 tapered roller bearings, all from Little Machine Shop. So no radical change in my plans at this point, just whether to make it as a two piece casting or one.

I'm itching to start the headstock while I have the time tomorrow. And with 95 views in so far, seems the yay's have it over the nays with the majority abstaining. I'll check back in the morning before grabbing a piece of timber in case there's a shift in opinion, and then probably start cutting wood for a split bearing housing headstock pattern.
Title: Re: Question: Split bearing housing for roller bearings?
Post by: PekkaNF on June 17, 2015, 02:57:41 AM
... grabbing a piece of timber in case there's a shift in opinion, and then probably start cutting wood for a split bearing housing headstock pattern.

PineCad-3D :lol:

Pekka
Title: Re: Question: Split bearing housing for roller bearings?
Post by: JonIndigoman on June 17, 2015, 03:09:08 AM
Hi Steve

My Acorn lathe which is a copy of the Atlas 10f uses timkin taper roller bearings retained in place with bolt on bearing caps. The bearing cups however have a lip to allow the preload but I would think you could deal with that by having a lip for the cup to press against on the inside edge of the bearing housing. There are lots of pictures on lathes.Co. uk of the various clones of this lathe.

Jon
Title: Re: Question: Split bearing housing for roller bearings?
Post by: Country Bubba on June 17, 2015, 08:35:05 AM
IFRC, I have seen some differential cases for automotive purposes built that way and the stresses there can be quite high.
I say go for it. 
I think the main reason a lot of manufacturers do not do something like this is because it would add cost to their product. Just making a hole is simple on a production line, but to add a separate cap and a couple of bolts per bearing could get costly in their eyes.

just my .02
Title: Re: Question: Split bearing housing for roller bearings?
Post by: bertie_bassett on June 17, 2015, 05:59:46 PM
cant see any major issues with a split design, as long as the 2 halves cant shift once assembled. a stepped design between the 2 halves would keep everything aligned id think.
Title: Re: Question: Split bearing housing for roller bearings?
Post by: vtsteam on June 22, 2015, 07:31:43 AM
Thank you all for answering -- I'm going to go with it.  :dremel: :mmr:
Title: Re: Question: Split bearing housing for roller bearings?
Post by: mattinker on June 22, 2015, 08:26:45 AM
I can't see anything but advantages in splitting the bearing carrier. How are you going to drive the spindle?

Regards, Matthew