L/h - r/h sawmill mandrel

moodnacreek · December 21, 2017, 07:32:57 PM

Could I put the mandrel off a left hand sawmill on a r/h sawmill ? I'am thinking that the drive pins would have to shear completely to back the nut off. That would be a really bad wreck.

ddcuning · December 21, 2017, 07:35:59 PM

Is the nut reverse thread? If so, I would be worried that forces on the blade from sawing action may loosen the nut during sawing.

Dave C

Kbeitz · December 21, 2017, 07:44:08 PM

You could use a threaded split two piece locking collar.

moodnacreek · December 21, 2017, 08:19:07 PM

Dave: that's what worries me. I'm thinking because the saw is pulled against the pins nothing will happen.

moodnacreek · December 21, 2017, 08:22:25 PM

Kbeitz: I never thought of that, thanks.

ddcuning · December 21, 2017, 08:51:29 PM

I understand it is up against the shear pins, but still, the thought of a nut coming loose and a blade coming off gives me a full body shiver.

Dave C

Kbeitz · December 21, 2017, 08:56:05 PM

ddcuning · December 21, 2017, 09:02:47 PM

Kbeitz, does that thread on then compression locks in place? Think it would hold up if you hung the saw? Before I found my axles were allowing carriage movement, I hung the saw and it stretched the threads on the shaft but the nut stayed on meaning there was a lot of force transmitted after the pins sheared.

Dave C

Kbeitz · December 21, 2017, 09:12:25 PM

Quote from: ddcuning on December 21, 2017, 09:02:47 PM
Kbeitz, does that thread on then compression locks in place? Think it would hold up if you hung the saw? Before I found my axles were allowing carriage movement, I hung the saw and it stretched the threads on the shaft but the nut stayed on meaning there was a lot of force transmitted after the pins sheared.

Dave C

Yep that's the way it works... But I would screw in on behind the nut if you
have room to do it.

longtime lurker · December 22, 2017, 02:35:13 AM

I'm as hard up for a buck and as keen to rebuild/repair/recycle as anyone else but...
.
Some places you don't skimp and the thread direction on a mandrel is one of them. I don't mind cutting a few corners but severing body parts is a different story. If you really can't afford to change out the mandrel better to cut a new thread the "right" direction and machine down a new collar to suit.

Not worth the risk IMHO.

Ron Wenrich · December 22, 2017, 05:44:56 AM

I've had the nut loosed up a couple of times. You shouldn't tighten your nut too tight or you'll smash the collars. A loose nut will give you saw problems well before the saw comes off the arbor. The saw guides will keep the saw in place. You should be checking your saw nut when you sharpen up.

I've also sheared a few pins. That will spin the nut on the saw so tight you won't be able to get it off without a torch.

Gearbox · December 22, 2017, 10:00:26 AM

Shaft material is not real expensive . Have a new one made or the old one fixed .

Alligator · December 22, 2017, 10:10:55 AM

Quote from: longtime lurker on December 22, 2017, 02:35:13 AM
I'm as hard up for a buck and as keen to rebuild/repair/recycle as anyone else but...
.
Some places you don't skimp and the thread direction on a mandrel is one of them. I don't mind cutting a few corners but severing body parts is a different story. If you really can't afford to change out the mandrel better to cut a new thread the "right" direction and machine down a new collar to suit.

Not worth the risk IMHO.

This is the only right answer to your question.

moodnacreek · December 22, 2017, 08:15:28 PM

Thanks forum members for the intelligent and thoughtful answers. If I do it I am thinking now about turning off the threads and have it rethreaded. In my time I have had 2 mandrels made and one straightened and collar machined. It is not easy to find a shop that can make a sawmill mandrel properly. the shop that made the one I use now is closed and the shop I am familiar with does not straighten the new shaft before they cut the collars.

4x4American · December 22, 2017, 08:33:55 PM

My friend said to give Keith Fenner a call, he's in Mass. Said he does alot of old school type stuff. Here's a video of his shop..

https://www.youtube.com/watch?v=mwd94E26cdw

Another idea is to ask ole Bruce, I'm sure he may know a place that can do that properly.

longtime lurker · December 23, 2017, 12:14:41 AM

straight off the top of my head my gut tells me that beyond the immediate issue of needing a mandrel ASAP you might be better off to take a step back and think it all through.

Just to me - and y'know i dont know the details on size/age of equipment/useage etc - having already had 2 mandrels made plus one straightened seems like a lot.

So whats the mill? Power unit? Saw size? Log size and type? Size of current shaft?
What has occured to make the other mandrels unserviceable?

My gut reaction is that your shaft is too small for the saw/log/ power unit combination and that the long term solution is to get a heavier shaft but thats going to mean new pillow blocks at a minimum, and maybe new pullys though you should be able to machine the new shaft down to suit your existing gear on either end.
The money is in the machining as much as the actual shafting material... if you're only running a 2½" inch shaft then upgrading it to 3" isnt that much more in terms of materials and the labour to machine will be pretty much the same but in terms of strength its about a 30% increase.
May also be a case of just buying a complete 2nd hand husk with a heavier shaft and replacing the lot that way.

Might just be something to look at.

Ron Wenrich · December 23, 2017, 06:11:38 AM

I would think that any sawmill mfg would be able to make a mandrel that would handle your mill. Jackson, Cleereman, Corley, Frick, Hurdle, Meadows, etc. are still in business and make circle sawmills. They have the means to make them. D&D Sawmill Services in Chambersburg, PA has them in stock, as well as the bearing to go with them. If you're in that big of a need, give them a call. Knowledgeable people. Also, your saw doc should be able to give you some direction.

moodnacreek · December 23, 2017, 09:22:14 AM

You guys are good. I'm not broke down, just fooling around with some old junk and trying to help a friend. My mill is an old lane I put together in '95-'96 to replace a belsaw that I sold and still maintain. When I bought the lane it came in a package of 3 junk mills and 2 gas power units. All the mandrels where babbit and worn out. A local shop made a mandrel using the old fixed collar. I made a steel husk for spherical roller bearings [3 bearings] borrowed a machinist's level and dial indicator and spent a lot of time and still had .0002 run out at collar.
when I hit the first log the collar spun. Next I went to Lane tech and had one made right and learned how they do it. This shaft still runs very nice and cool. Thanks again and merry Christmas.