Modding a Rigid Bandsaw to cut steel

[JohnUlaszek]

Thought you guys might like this.
Paul Ruggles modded a Home Depot Bandsaw to cut at 80-120 and 170-250 surface feet per minute, perfect for cutting sheet metal and plate.
Hacked Band Saw

[parsonsj]

Damn. That thing just went to the top of my "gotta have" list!

I've been using a poor man's bandsaw recently: I clamp my jigsaw in a vise upside down. That works (sort of ... I still have ten fingers), but I'm always wanting a real vertical bandsaw. The $1000+ price tag has always put me off.

Is Paul up for making more?

jp

[JohnUlaszek]

John,
I talked to Paul about building more but he wants to do some durability testing before he takes that on. Send me your address so we can get one down to you to test.

John

[astroracer]

Hey John!
Perfect timing on this one bud! I just bought a 12" wood band saw off eBay for less then 100 bucks including shipping. This saw has a variable speed but it is still too fast. This was my plan to convert it over to cut steel... Any chance on getting specifics for us other D.I.Y. guys? Pulley sizes would be excellant.
Mark

[JohnUlaszek]

Mark,
Paul came up with a design and mechanism that works for the Rigid and maybe the Habor Freight but your drive mechanism, motor speed, and room for packaging will drive your design.
The pulley diameters we used probably won't help you as we are starting with a different motor and pulleys and the wheels on the saw itself are different diameter.
I believe the machinists handbook has some pulley calculations in it. Your first task will be to see how many SFPM you machine is right now.
Sorry I can't be more specific, but its a bit of an engineering problem with unknown variables. Initially we had hoped to just swap pulleys, but that would have actually sped the thing up. It's not trivial to slow woodcutting saws down to the usable speed.

[KWIKND]

What about a freq drive(variable frequency drive)? Slow the motor down while maintaining full torque. We use them on overhead cranes 0 to 150% speed - 250 ton hoists.
Dan

[JohnUlaszek]

Dan,
We thought about that, but we felt a pulley system would be the cheapest route and would allow the motor to operate at its designed RPM. The motor on the saw is a single phase 110v motor and is only rated at 1/2hp. Freq drives are not cheap but If you think you can get one working let us know how it turns out.

John

[KendallF]

Great idea! I have seen a few other people try this..and I was just in Harbor Freight today looking at the metal bandsaw they have for $159 and thinking that it'd work, but 4 1/2" throat depth isn't going to allow cutting bigger stuff.

I have a question: how does the wood blade do for cutting steel, and is the blade length a common size where you can swap for a blade with appropriate TPI count for steel?

[JohnUlaszek]

The wood cutting blade is useless for cutting steel.
We switched over to a Starret 14-18 skip tooth blade. At 80 SFPM it cuts sheet metal like butter and its quiet. THe 93.5" blade is a standard size for cutting metal.

[astroracer]

Thanks John,
I figured I would have to recalculate blade speeds and pulley sizes for my saw. I guess I was more curious as to what bearing blocks or jack shafts you used. I probably should have asked that rather then pulley sizes...
Thanks again.
Mark

[JohnUlaszek]

Mark,
We used standard .750" keyed shaft available from McMaster Carr. The bearings are sealed cartridge bearings in a machined block. Calculating pulley ratios and then designing the thing to have proper belt tension is critical or the blade will stall on heavier cuts.
The pictures don't show how it attaches but it has a frame that ties the motor and saw together at the base and makes it much more rigid than the factory setup. Paul is thinking about selling these if there is enough interest but only after he has had time to work out all the bugs and do some durability testing. John Parsons has agreed to test one out and see if he can break it.

[parsonsj]

Yeah ... somehow I talked Paul into sending me his prototype. I'll give it a solid go, and report back here in a week or two. I have some sheetmetal and tube work (both steel and aluminum) to do, so I will exercise the saw a bit.

jp

[astroracer]

Sounds good John, and thanks for the info. I was scoping out parts in both McMaster-Carr's and Grainger's catalogs yesterday. I also went out and dinked around with the 12" variable speed saw I bought and decided it's not worth messing with. I will leave it alone and use it for cutting wood only. It's got a small motor on it and the variable speed leaves it with no torque at metal cutting speeds... No great loss for 70 bucks. I will be picking up one of the bigger 14" saws shortly. Do you have any suggestions or things I should be looking for different then the Rigid saw? I will be checking out Harbor Freights offerings and Sears has one that is similar so I should be able to come up something that will work.
Mark

[JohnUlaszek]

Mark,
The harbor freight model can be caught on sale for $229.00 and is worth considering on price, but of the higher quality models the Rigid seemed the best bang for the buck.

John

[parsonsj]

Well, after convincing the concerned sales staff at my local Home Depot that they actually do have such a saw and that their job is to find it and sell it to me, I drug one of the 200 lb beasts home today.

Paul's conversion kits will be here this week, so I'll have some reaction about this inexpensive metal bandsaw experiment next weekend.

jp

[Jim Nilsen]

Hey John, I did the same thing to my Jet wood bandsaw and it works great.Jet actually had a kit to adapt over .

If you can ,you need to make it so you have a speed right in the middle or a little faster for cutting aluminum. I use a larger pulley on the drive wheel to do it.

Wood blades work great for cutting aluminum when set at the right speed. A wire clean off wheel helps a lot too for blade life. My saw right now will cut through half inch aluminum 6061 t6 like butter. The variable tooth blades under 12T work the best.

I had just seen a 2 in 1 Delta in a local Farm & Fleet and in there catalog that had the lowered motor and jackshaft setup for being able to go slower. It was only $300 and the wood bandsaw only was $ 400 go figure ? If I didn't already have one I would have taken it home with me !

Goodluck , Jim Nilsen

[parsonsj]

Hi Jim,

Been a while since we've heard from you. Welcome back!

I checked out the Jet speed conversion kit and it seems a bit fast for steel: only 725 sfpm as the slowest. That's too fast for steel, but may be ok for aluminum. The Delta 2n1 is EXPENSIVE: $1600! At least new it is, anyway.

This Rigid deal is $350 for the saw, and $200 or so for the kit. Paul is verifying the actual speeds with a tachometer (must be something different than what I was thinking of ), but thinks he got somewhere around 40 sfpm up to about 120 or so (it's adjustable).

Anyway, I'll post when I have some actual run time on the saw.

jp

[astroracer]

I just bought an older, taiwanese style 14" saw on eBay for $132.50. It is supposed to be a dual type saw. Wood and metal. Used very little and kept in storage, out of the weather. I will be picking it up Saturday.
Obviously I can't give you any info until I get it in my shop and check it out but this was a hellofa deal and I'll be able to throw some time and money at it too get it up to speed.
I will post some pics next week.
Mark

[JohnUlaszek]

The thing to keep in mind is that you need to be down around 80 SFPM minute to cut sheet metal properly. Most of the dual purpose machines have a low speed that is way too fast. They claim they are good for metal but are typically around 700 SFPM on the low speed which will cut aluminum sheet but not well.

Let us know how your machine works and if you can mod it to run slower.
There is a real need for a hobbiests band saw for cutting steel and as of yet Pauls solution is the only one I would consider affordable if he decides to start making them.

John

[BADVELLE]

Great idea! I have seen a few other people try this..and I was just in Harbor Freight today looking at the metal bandsaw they have for $159 and thinking that it'd work, but 4 1/2" throat depth isn't going to allow cutting bigger stuff.

I have a question: how does the wood blade do for cutting steel, and is the blade length a common size where you can swap for a blade with appropriate TPI count for steel?

I bought that vertical/horizontal from Harbor Freight thinking it would be great for my shop use. I have adjusted and re-adjusted and it still throws the blade almost everytime. I am only cutting 1/16" plate and taking my time at that. I am just done fooling with it, going back today. I just believe I actually paid for what I got, a piece of crap!! I always say, you can't polish a terd and in this case I seem to be right!