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Rockwell Delta 20” vertical bandsaw question 28-3X0

Peglegfablab

Plastic
Joined
Apr 12, 2024
Location
St. Louis MO
I have a Rockwell / Delta 20” vertical bandsaw that I want to cut mild A36 and other steel on. This model saw was built for government school wood shop applications.

The saw is a single speed setup and geared for wood cutting speeds. I need to slow it down to roughly 85-250 linear feet per minute to cut steel with.

I can’t find any info or videos out there where anyone has made changes to this model saw for this application. Anyone on here dealt with this and have info on it?

The saw is 3 phase but I don’t want to use a VFD to manipulate the motor speed as I don’t think that’s healthy on the motor.

I can possibly change the motor out to single phase with a different RPM which may be easier than finding dual belt pulleys to change gearing reduction. Is there a good source out there for pulleys?

Thanks in advance for good advice
 
You bought the wrong saw. Their 28-365 was fitted with a 2 speed gearbox and variable speed drive. I found it great for both metal and wood.

Slowing down a bandsaw is a frequently raised issue. If you decide to use belts, pulleys and a jackshaft have a look at the belt section of Machinery's Handbook. There are limits to the power you can transmit between a vee belt and pulley without having slippage.

I very much doubt your motor would be hurt by using a VFD. However, if you slow the motor down 90% (to go from 3000 sfm down to 300) you will lose nearly all of your torque. This is fine on a belt sander because you only need the real slow speeds for running super fine grit belts which don't load the motor much at all. But a drill press or bandsaw often is asked to do the most work at the slowest speeds. Just something to consider.

I suggest looking through old Popular Mechanics for articles on this subject. I have seen some very clever ideas in there over the years.

metalmagpie
 
Get a different saw.
The 20" is a big honk'in saw. It is not the consumer size 12" saw.
It is the size of a Grobb or Doall 1612.

I am thinking a 7.5hp motor with a VFD would still have decent
torque down low for metal applications.

-Doozer
 
You need roughly a ten to one speed reduction. A ten horsepower motor at 10% frequency might work if you add cooling fans. I have seen pictures of dual motor drives. Only one motor powered at a time. the extra motor just coasts along, driven by the other.
GEAR motor?
Bill D
 
I bought this saw probably 7 years ago with the plan to use it dual function of wood and steel cutting. I figured it would be a challenge to modify it but hey, I’m all about modifying things see.

I haven’t used the saw and it stuffed in a corner of my shop. I’ve thought about selling it but I’m having a hard time convincing myself to do that as I’m a tool addict and love old machines.

I recently bought a powermatic 81 20” vertical bandsaw that was built for same application as my Rockwell Delta. I bought it at a deal I couldn’t pass up and planned on flipping it. But nope, I can’t bring myself to sell it either. I love how it’s built.

I have a use for both saws really. I have two shops that I’m in the process of having three. One (the big one) will be my steel fabrication shop, my half basement wood shop will become my machine shop which is in my fab shop. Then my wood fab shop will be in my 2 car attached garage on my house. Growing pains.

Long term plans are to get a CNC plasma table in the future, but in the meantime I’ll use my buddies table and at home use my hypatherm 85 free hand and try to use my Rockwell / Delta bandsaw too.

If it’s just too much of a pita to slow down or too much cost related, then I’ll sell it off. I’ll sell it over the powermatic as it’s built a lot beefier than the Rockwell / Delta is.

Anywho, that’s all the reasons behind why I want to slow it down.
 
Around 1980, I designed a two-speed (1:1 and 12:1) belt drive for my 12" Craftsman wood-cutting bandsaw to allow changing from wood to steel cutting speed in a few seconds. It worked fine, but the diecast aluminum frame was not really stiff enough for heavy work. I sold the Craftsman saw after getting a used Powermatic 143 with a geared transmission and properly heavy construction for cutting steel and still have it.

The 20" Rockwell and Powermatic saws are plenty heavy enough for cutting steel and were sold with slow speed drives for metal, so a two-speed belt drive would be an inexpensive solution if you can design it. I do not have drawings or pictures, but the key was using two-groove pulleys in two places and a lever belt tensioner for changing speeds and shifting the drive belt from one pulley groove to another. The original single speed motor was retained.

Larry
 
I have the same saw but with a gearbox. Just sell it and buy the correct saw. I tried just slowing a wood cutting saw down once. Doesn’t work without mechanical reduction.
 
Pete, Grob did it with no gears. Just lots of pulleys and jackshafts. I believe they had four or five belts to be shifted around. They have since switched to a high low gear transmission and maybe a Reeves drive on that as well.
BilLD
 
Some decades ago I had many hours on a friend’s Rockwell 20” metal and wood cutting bandsaw. Reasonably rigid saw. Cut plenty of steel up to 2” thick on that machine. The low speed gear box and Reeves drive is a direct drop in from the wood only saw version from that manufacturer. I’d suggest looking for a scrap Rockwell metal/wood saw- most likely one where a guy has tried to lift from the table and broken the trunions, or one tipped on its side and busted up. Grab the gear box and Bob’s your uncle.

Or just buy a DoAll and sell your current saw.

(r.i.p. Bob)

Cheers,
L7
 

I went to a local trade show and a booth was giving away free magazines. I picked this one up.
There a 9 pages with pictures. Done by inserting a shaft with pulleys and belts in between the motor pulley and the upper band saw wheel.

Converting a Woodcutting Band Saw to Cut Metal by Jim Gavin
 
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Sell one or both of the wdwrking saws and get a PM 87. 2 speed gearbox and reeves drive - can go from top speed top bottom speed in less than a minute. There's more of those around than the Delta version, can often be had for under $1k

edit - Also, if you go to sell it, more valuable than modified version
 
I see the prevailing suggestion doesn't favor converting it, so I'll throw in my two cents...

Three-and-a-half decades ago, I was given an old Craftsman (1950's era) woodcutting saw that someone had put a metal-cutting blade in it, and found it to be spinning way too fast... it came to me without motor or drive belt... or even a drive sheave.

About the same time I came across a worm-reduction motor in a scrapyard that the motor was burned up, but the worm reducer (about 12:1 or so) was still good.

I took the motor apart, pressed the shaft out of the rotor, cut a ring out of the motor shell (to shorten it) and reassembled it, put a belt sheave on the input. The saw had no sheave, so mounted a #40 chain and sprockets from the worm drive, and stuck a 1/2hp motor on a belt driving it all.

It isn't the most ghastly powerful thing on the planet. It isn't the most rigid, either... but if I have to whittle a shape out of a piece of 1/2" mild steel plate, it WILL do it a whole lot faster than I can with a file... and a whole lot cleaner than with abrasives. 1/4" is fairly swift, and 1/8" is downright quick.

At the time, I didn't have any of the machine tools that I have now, but I had a cheap hydraulic press, a cordless drill, a 4" grinder, sawzall and a flux-core MIG... and that's all it took to expand my fabrication capacity significantly. Nowdays, I have significantly more in my arsenal, and I have significantly more funding available to buy things... but I still have that old saw, and I still use it about every week... it's in my small shop, right between the (too small) blasting cabinet, and that same cheap hydraulic press. About eight feet away is a similar bandsaw with a woodcutting blade that I use to whack away smaller pieces of wood, plastic, and aluminum before carrying them in for more delicate shaping.

So it really comes down to what you want, what you need, and what you have. If he's got everything he needs to make a functioning tool, make it happen and move on, and if it isn't enough to do the job satisfactorily, get the better machine going, and move the old one out.
 








 
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