Belt tension on a lathe

[Mike Cruz]

Okay, the title might be a bit misleading because this is a stealth "do I really have to" thread.

I'm putting my PM90 back together. I got the bed bolted back onto the base. The bed is quite heavy, so I had to get someone to help me do that (Peter, thanks a million). I put a bunch of the other parts on (that I could at this stage) and got to the motor. I am replacing the stock 1 hp motor with a 2 hp motor I got of Ebay. Reminds me...gotta post a gloat on that one. :D The motor mounts to the motor mounting bracket in the base cabinet. I went to put the long bolt in that goes from the motor mounting bracket to the...uh-oh...base. :o Yeah, the hole for the bolt in the base is riiiiiight under where the bed sits on the base. Yes, there is a gap for the head of the bolt because there are rubber washers between the base and bed.

The belt from the motor is a standard belt (I used a linkbelt) that goes from the motor pulley to the jack shaft. There is another belt (for the Reeves drive) that is totally unaffected by this prediciment.

So, this leads me to my question... Do I really have to use the tensioning bolt to tension the motor, or will the weight of the motor be sufficient? This motor is pretty substantial with a 7/8" shaft.

Thoughts?

[Dennis Ford]

I have used motor weight to maintain belt tension before. It works but is not an ideal solution, changes in load cause the motor to move up and down a little creating extra vibration.

[Steve Schlumpf]

I agree with Dennis - the motor - if left unattached will shift!

[Roger Chandler]

Ditto what Steve and Dennis said!

[Mike Cruz]

Ugh :( Peeeeeteeeeerrrrr? I have beeeeeeeer...

[Peter Elliott]

okayyy, tell me when.. That Troegs was pretty good stuff too!

[Mike Cruz]

You can't see me, but I'm leaning back, setting the hook! I just hope my drag is set right so the line doesn't snap! Busy tomorrow? :D

[David Reed]

Put a bungy on it.

[Mike Cruz]

I actually need to have pressure down, the bolt acts as a spacer keeping it away from the base, not pulling it in. There is no way to attach a bungy underneath to pull it down. And I have a feeling it wouldn't be enough pressure anyway. I suppose an option would be to use some threaded rod and a lock nut, IF I could slide the nut between the bed and stand. I might look at that, but it sound like it might be a lot more work than doing it "right".

[bob svoboda]

Be glad to help (for beer) but it's a long hitch-hike :D

[Mike Cruz]

After further review of the play...I'm an idiot. :o Well, I never would have known I was an idiot if you all hadn't insisted that I hook up the bolt.

Before I got back into the shop, I thought about the process of disassembling the lathe. Something didn't seem right. I didn't remember having to remove the bed to get the bolt out. Also the space between the bed and the stand isn't more than the head of a bolt, so the bed would, in essence, be resting on the bolt...

So, I went back in the shop to take a closer look. Oops, the bolt doesn't go through the hole in the base (the other thing that seemed wrong...seemed like it would be a bit flimsy), it screws into the BED!!!!! Yup, there is a threaded hole in the bed riiiiight where the bolt should go.

BTW, I have NO idea what that hole in the bed is for. Hope I don't find out later...

So, Peter, thanks for the offer, but I won't be needing your brawn.

Thanks all, for pushing me to lock 'er down. I'm much happier now.

[Peter Elliott]

Hey, we had a deal! I lived up to my end... now it's your turn!! Troegs.....

Glad it worked out but I still want the beer :p

[Mike Cruz]

Anytime! Hey, I just got a couple more cortisone shots in my arms today. I'm not doing diddly today or tomorrow. Actually, I just got done watching Wolfman (the new one). I picked up a Wii a couple days ago, and I'll be setting that up tomorrow. I can drink...