Jet JBS14-MW - Metal/Wood Bandsaw - Slowing to cut steel

[datmony]

Jet JBS14-MW - Metal/Wood Bandsaw - Slowing to cut steel

--------------------------------------------------------------------------------

Hey everyone, happy almost new year. I got a great deal on an older Jet Band saw, the JBS14-MW. This saw is very similar to many of the other Taiwanese saws out there from Rockwell, Delta, etc.

This one has an intermediate pulley system that allows it to be run at a few different speeds by moving the belts. However with the current pulleys and set up the slowest speed it will run is 700 FPM which despite being noted as a dual use saw is still way too fast for steel.

I want to get this down into the ~100 FPM range to be able to cut steel. I well run a bi-metal blade with roughly 18 TPI.

With that application in mind, I have a few options:

1. Try to use just a pulley change and utilize that to get to the correct speed. One of the more simple methods but not sure I can get it slow enough by simply doing that.
2. Run a gear reduction box of some sort.
3. Run a DC motor with a controller so that I have variable speed.
4. Combination of any and all of the above.

I am heavily contemplating option 3 and have found a couple DC motors with a gear reduction box already on them as well leading me down the option 4 path. I like that idea so that I have virtually infinite speed adjustment on the saw.

What are folks thoughts here? What have you all done on yours? Can you post some pictures of conversions that you have done? Would love any and all insight. Also, I do plan to also plan to install some brush blade wipers to keep metal chunks out of the tire and would also like to see any pictures of what you might have done there.

Thanks in advance.

[velocette]

Hi
The DC motor and gearbox seems to be the way to go with an extra pulley on the counter shaft to take the drive from it.
Retain the original motor and drive for wood cutting.
Consider using "Poly Vee Belts" for the drives much better performance than "Vee Belts".
Make sure that the motor you use has enough power for the job and use a commercial AC to DC speed control.
They are a bit tricky to set up to match the motor but give you a great performance and overload protection.
My work shop machines are all on DC motors except the vertical band saw it has a motor and reduction gearbox (18 to 1) with 3 speeds from "Poly Vee" stepped pulleys for steel cutting and the original motor for wood work just remove the belt from the gear drive
Keep us posted on progress

Eric

[RWO]

I have a Delta wood/metal, similar to your saw. You will need a gear box with timing belt or chain/sprocket output to transmit the torque to the bottom saw wheel to cut metal at 100 FPM. Wheel RPM will be about 27 with 14" wheels. Standard V-Belts/pulleys won't do it without slippage.
The brush wipers are useless. Just change the tires to polyurethane. A certain amount of metal chips will embed, but it causes no problems.

RWO

[bosox]

No experience yet with converting band saw, but I would opt to gearbox to get the work right.

[Alistair Hosie]

Even better for speed reduction with good torque is a vfd and three phase motor.This way you get the best of both worlds. Alistair

[lakeside53]

Mine's the 4 inch Wilton-Jet wood/metal version - 20:1 reduction at the pull of a knob. Uses standard V-belts for input; gearbox directly drives the lower wheel.

[Rex]

I bought that exact same saw last winter, and went through the same process. I could have written your post. In fact, if you look through PM archives you will probably recognize it.

What I did was pull the motor and the intermediate shaft and pulleys. I used a 60 rpm gearmotor which just happens to put the speed at 105 FPM. Easy conversion, works great. Plus, the 110V motor was exactly what I needed to replace the 3-ph motor on a horizontal bandsaw.
In my case the decision was easy. I already had the gearmotor, and it just happened to be perfect. I understand those 60 RPM motors are pretty common, used for Assembly lines and possibly small conveyors?
Lacking that, I would have used a variable speed setup, either DC or 3-phase with a VFD.

[ed_h]

I added a gear motor alongside the original motor. It's just a matter of moving the belt.

Pics:

http://bullfire.net/Bandsaw/WP_Delta_Bandsaw.html

[EVguru]

I have a Startrite Bandit 5 (it's the 5 speed model) which says it can cut Aluminium in the lower speeds. With an HSS endged blade and running the motor at 20Hz via a VFD (A Eurotherm with a confusing menu system and a manual far worse than even the early Huanyang one!) it cuts steel just fine. It does lack torque and you can stall it by pushing too hard, but the VFD just drops speed gracefully, so you just back off to resume cutting. It's on the list to add another reduction stage and a cabinet stand.

[JohnAlex141r]

I did mine about a decade ago, just put another shaft in there.

Someone from France was asking, so I put some pictures on my blog of it:

http://cnc-for-model-engineers.blogspot.com

It was so painless, and so successful, I had to actually go and open up the base to see what I did all those years ago.

I do cut the odd bit of MDF on it with the metal blade, just go slow, and it works fine - but that's not a woodworking experts opinion, just my "I need to cut this now" opinion.

Is my saw anything like yours?

John.

[metalmagpie]

This question comes up all the time, and has forever. I remember an old Popular Mechanics article in which the author had a turntable. To switch to low speed he rotated the turntable putting in position a worm gear reduction unit. To run at full speed the turntable had 1:1 pulleys mounted on a shaft. Don't remember the details but it looked slick.

Before you simply try slowing down the motor with a jackshaft you should go read Machinery's Handbook on how much horsepower can be transmitted by vee belts as a function of speed. At low speeds they tend to slip, hence the suggestion above to go to a chain drive, which guys have done with bicycle sprockets and chain inexpensively.

metalmagpie

[jlevie]

My personal experience is that those that say transmitting the torque with v-belts will be a problem are totally correct. Years ago I tried this using pulley speed reduction and found it unsatisfactory. At ferrous metal cutting speeds, the belts would slip if cutting anything much thicker than 1/8". I solved that with a gear reduction drive coupled to the lower wheel shaft and then found that the saw frame simply wasn't stiff enough to maintain blade tension under the varying loads that hand feeding produced. The end result worked, but for the effort and money I put into it I'd have been better off finding a used bandsaw designed for ferrous metal cutting.

[Rich Carlstedt]

Only way to fly, Direct drive. Positive drive and speeds of 44, 88,125 and 180 Ft per minute
Great for SS , steel, CI ,brass and Aluminum. Works on wood too
Rich

[JohnAlex141r]

My personal experience is that those that say transmitting the torque with v-belts will be a problem are totally correct. Years ago I tried this using pulley speed reduction and found it unsatisfactory. At ferrous metal cutting speeds, the belts would slip if cutting anything much thicker than 1/8".

Bijezuz - you mean what I've been doing for a decade plus is not going to work? Last thing cut on mine was 3/4" cold rolled. Maybe I should look and see if it really cut! (smile)

Sure beats hacksawing - so I'll stick with my converted bandsaw, thanks!

Certainly, it's not as good as a designed-for-metal saw, but it's more than adequate for my uses. I have used made-for-metal bandsaws, and they are certainly great, but I'm more than happy with my converted saw.

John.

[brian Rupnow]

If at all possible, get the transmission off a junked riding mower and incorporate it into your pulley system. Then you don't have to dick about changing pulleys, belts, etc. Just change to the gear which gives the speed you want.