I see what you mean, and I'm considering something along those lines. However, this also needs to have some kind of quick-release mechanism, so I can shift the belt from one motor to the other with a minimum of fuss.

Leave the threaded rod stickout short and have an appropriate sized socket drill bit in a little bag pinned to the frame? That's what I do for my break-down workbench and it's really nice if you always have a cordless drill somewhere nearby.

  Come to think of it after I drew this one, just do away with the all-thread assembley and the one of the hinges and just use a rubber tipped toggle clamp.   Sorry for the sideways picture.   Quick change and stability!

I've been thinking about something that doesn't require tools, and I will definitely add this to the "possibilities with toggles" mental file.

I've been listening to a lot of Adam Savage's "Tested" videos lately, and he talks a lot about "First Order Retrievability" for his tool storage: the idea that you shouldn't ever have to move one tool in order to get the tool you want. In thinking about a lot of the processes of my shop, I've realized that a lot of the things that I never get around to doing are things that I've unwittingly made more difficult for myself by setting them up in a way that requires additional steps to achieve the desired end. In this particular case, if I can reduce the motor switchover procedure to <release motor 1 lock> / <move belt from motor 1 to motor 2> / <engage motor 2 lock> without having to go fetch another tool from somewhere else in the shop (assuming I put it away in the right spot in the first place!), that means I'm much more likely to switch back and forth whenever I want to rather than when I HAVE to.

Update: went to do some cutting yesterday (metal), and noticed that the blade had stretched sufficiently that I needed to retention the saw. Unfortunately, it seems that the tensioning mechanism isn’t working, and it was only sheer luck that the blade had been at the proper tension previously. So, I’ve got something else to take apart and fix.

Update: still playing with ideas for drive belt tensioning. In the mean time, I discovered an interesting (and easily solved, for once) little problem: the tensioning mechanism wasn't working. When the blade was new and I first rolled it onto the wheels, it just happened to be at the right tension. After it stretched out a bit, it kept bogging down, even though the motor, belts, and drive wheel were still turning just fine. After a futile attempt to tension it, I took the upper wheel mount apart and discovered that the slide on the tensioning mechanism was jammed. A bit of oil and some steel wool to remove a bit of rust, and we are back in business.

In other news, I just ran across this ad in my local FB marketplace, where it looks like someone decided to go the jackshaft route:

How much do they want for that rig?  Just curious.  I'm looking to sell my homespun power hacksaw...

They're asking $200.

  Much appreciated.  I know it's a bit like comparing the price of tomatos to potatos but it gives me an idea where to start.  I must say I undervalue some things horribly.  Maybe it's my geographic area.... 

I have absolutely no clue what the market in homebuilt metalworking machinery in Nebraska might be like. 

Update: the blade was still bogging down after I fixed the tension mechanism. Further examination revealed that the setscrew holding the drive pulley in place had come loose, allowing the pulley to spin when the saw came under load. A few twists from an Allen wrench, and we're back in business.

In other news, I did my first switch from metal to wood, which went quite well. The only issue that presented itself was that the stand has too much flex in it, and the higher speed was making the whole setup wobble in an unsettling kind of way. I guess I need to build a new stand, which means I'm glad I didn't invest too much time in figuring out a tensioning mechanism!

John,

Just be careful about wood dust buildup inside the saw and hot metal particles hitting same after you switch over in that direction.

Oh, yes. 

Aaaaaaaaand we’ve got problems. 

I was cutting some 1/4” plate when everything stopped dead. I went to check the box, and sure enough, that breaker was tripped. Clicked it back over, went back to the shop, and nada. There’s power in the circuit (I tested it with the grinder) and I can hear and feel the motor humming, but the output side of the gear drive is locked up solid. 

I’ll probably have to take the reducer apart to see what’s going on, but it’s too nice a day to get bummed out about this now. I’ll set it aside to fix some other time. 

  Did you ever get it back up and running?  Did the gearbox melt down?   I may have missed it elsewhere.  Just curious.

No, not yet. The Great Welding Cart/Torch Stand Build intervened, but I do want to get back to this soon.

I did get the side off the gear reducer, but didn't see any immediate problem -- other than the oil that promptly spilled all over the floor!

Everyone have good bandsaw,

I'm just checking for the Rikon, Its looks good after checking [commercial link removed] about it. There are good vibes from there but i'm little bit of confused about it.

If any one using this than suggest something.

Edited July 6, 20214 yr by Mod34
Commercial link removed per TOS

On 12/14/2020 at 9:39 AM, JHCC said:

Maybe a manual gearbox with four forward speeds and reverse?

I used a VW bug 4 speed to run a Camel back drill press. Worked very well indeed. 

Back then there were a lot of descent camel backs around for cheap and that drill press was replaced by larger and larger units.

  I'm still interested in this project.  Any progress?

  Scott.

No, not yet. Don’t worry: I will update this thread when I do anything, regardless of the result. 

  I rest assured and will no longer pester you about it, but wait for an update.    Which I have faith will be good.

This was how I set up my bandsaw about 10 years ago, Its a wood bandsaw but a really old school over built one and I fitted a 20/1 reduction gearbox that pivots on a hinge at floor level the tensioner is off a trailer jockey wheel and has a coarse pitch thread so its fast to move. I was fortunate that the gearbox has three step reduction so the rotation direction does not change from input to output or I would need a reversing switch. With the reduction the blade speed is about 1/10 of the fast speed for wood and aluminum, I use 10TPI Bi metal blades for every thing. I positioned the output pulleys so the belt length is the same over the two pulleys so use the same belts. The bandsaw used to run at 760 M/Min which was really going but my speeds are 585 and 55 M/Min or if I put a 75mm pulley on the step down box it will go down to 42 M/Min but i have never used that speed yet. the guard is hinged so just swings out of the way to quickly change speed and to keep the Osh man happy and stop the body pit from getting any fuller. It has a 2Hp 3 phase motor. The bandsaw was out of an undertakers from one of the neighbouring districts and I assume it was for making the coffins and not changing the victims length if He made a mistake in measuring LOL.

Long overdue update: I still have not done anything about fixing the gear reducer, although I do still use the bandsaw for wood projects. However, I did just come into possession of a (free!) 14 inch Taiwanese bandsaw with a cast iron frame and a built-in set of step pulleys on a jackshaft.

Unfortunately, the manual that I got off eBay

()

doesn’t contain information about the extra pulleys and their speeds, but I have done a bit of math and I’m not sure this will work without additional modification. Somebody check my work, please.

The two step pulleys have a small diameter of 2-1/4” and a large diameter of 4-1/2”. The pulley that drives the bottom wheel of the bandsaw is 6-3/4” (actually slightly larger, but I rounded down for ease of calculation). If I run a belt from the smallest step at the motor to the largest step at the jackshaft, that’s a reduction of 1/2. If I run a belt from the smallest step on the jackshaft to the drive pulley on the saw, that’s an additional reduction of 1/3, for a total reduction of 1/6. Since the motor spins at 1720 rpm, that means the wheels on the saw are spinning at 286-2/3 rpm. Since a 14” wheel has a circumference of 44” (or close enough as to not make a difference), that means the blade is traveling at 12,613-1/3”/minute or 1,051-1/9 sfpm. That strikes me as still too high. Thoughts?

 

John, I will check the diameters of the wheels on my band saw and post them later today and see if they are in the same range.  It may be that your saw is designed for wood work which ususally has a higher saw speed.

GNM