Band saw conversion, wood to metal

[dustboy]

So I have this nice 14" Jet 1 HP bandsaw, all set up with Carter BB guides and a Kreg fence system. Cuts wood like a champ, square and straight.

Then I started doing a lot of metalwork on my rig. I can cut a lot of stuff with my chopsaw and jig saw, but that's a drag. It would be sweet to cut metal with this fancy bandsaw..only problem is the blade moves waaay too fast. Like 3300 IPM, when mild steel wants to cut at around 300 IPM (correction invited). I don't have the space or money for a horizontal saw.

I did try just putting a 14 TPI metal blade on it and using some cutting oil, which worked for more cuts than I expected, but after the teeth started breaking off it got progressively harder to cut.

So, slow the thing down. To get enough reduction I will need to add a jackshaft, and even then there isn't enough room to get a ratio of more than 14:1 compared to the original 2.4:1.

I'll spare you the math, but it looks like I can get the blade speed down to 561 IPM. And I'll add a coolant mister just in case.

The plan:

Motor: original 2.5" pulley
Jackshaft: 7" pulley to 2" pulley
Drive shaft: 10" pulley (originally 6")

I just ordered the parts from McMaster-Carr. Here is the list:

1 1 Each 6245K953 Die Cast V-Belt Pulley 4L, A-, & Ax Section Belt, 10" OD, 3/4" Bore $23.21

2 1 Each 6245K16 Die Cast V-Belt Pulley 4L, A-, & Ax Section Belt, 2" OD, 5/8" Bore $3.25

3 1 Each 6245K53 Die Cast V-Belt Pulley 4L, A-, & Ax-Section Belt, 7" OD, 5/8" Bore $11.50

4 1 Each 1497K108 Fully Keyed 1045 Steel Drive Shaft 5/8" OD, 3/16" Keyway Width, 9" Length $17.73

5 2 Each 6244K52
Cast Iron Base-Mounted Steel Ball Bearing Set-Screw Lock, for 5/8" Shaft Diameter $33.67

6 1 Each 11365K63
Biodegradable Misting Coolant Concentrate Kool Mist 78, 1-Gallon Container $29.48

Total $152.51

Stay tuned, I plan to put it together this weekend and I'll post the results. Oh, BTW Jet does sell a speed reduction kit for this saw, but it only gets it down to 750 IPM, which I figured was still too fast.

 

[spencyg]

I used to run Kool Mist in my shop, but after continually getting sick with sinus infections, I stopped. That stuff is nasty. If you use it, ventillate well.Flood cooling is really the best, but it is hard to do with a vertical saw. Most guys using a vert. metal bandsaw just wax the blade and go for it. At 500 ipm you should be ok....won't get hot anymore. Get nice Lennox blades...everything else is crap.

 

[ntsqd]

What is the motor's rated speed?

 

[dustboy]

What is the motor's rated speed?

1725

I know, I thought the same thing. Get a slower motor, but I guess AC motors only run 1725 or 3450.

My dad's neighbor used a DC motor with an electronic variable speed control, but that would probably cost more than a basic horizontal saw.

 

[dustboy]

Okay, it took a couple trips to the auto parts store to get the right belt size but it works! Seems like a very good speed, not sure if my calculations are accurate or not, there is a lot of confusing info about blade speed on the web, and a lot of statements seem to have the wrong units.

Anyhoo, here are some pics:

The upper pulley is 10". It needs a safety cover. I had the atomizer laying around, I filled it with the Kool Mist mixture. Seems effective, if a little messy. Added a regulator to the atomizer so it wouldn't be blasting coolant everywhere.

Looking down, the jack shaft is obscured.

Close-up of the jack shaft and bearings, looking down into the motor cabinet.

Inside the motor cabinet. 2.5" pulley on the motor, 7" pulley then 2" pulley on the jack shaft.

 

[ntsqd]

If it is a 3 phase motor you can buy a speed controller that runs off of single phase. Odds aren't good of that being the case. I'm pretty sure that we have three of them on my project at work.

 

[spencyg]

Yeah a VFD and 3 phase motor would be the way to go. This is how I run ALL of my equipment in the shop and it is slick. An inexpensive VFD can be sourced from automationdirect.com, and used 3 phase motors are a dime a dozen on ebay....

 

[dustboy]

Variable speed 3 ph offa 1 ph? Now ya tells me. Anyway, I sliced up a lot of 1/8" plate to finish my front bumper, it cut very nicely, straight clean and cool.

 

[spencyg]

You would still need reduction, as a 3 phase motor won't last all that long run under 30 Hz (1/2 speed)....they get hot. On my primary drill press I have it geared way down, and then use the VFD to give me from around 30Hz up to around 180 Hz. Obviously this provides from 1/2 motor speed up to 3x rated motor speed. I also always use good (I.E. Baldor) motors....a cheapie 3 phase will start coming apart when run at higher speeds. Another really nice thing about a VFD and a 3 phase motor is that you can tune the ramp and electronic brake characteristics....this is critical if you're running a very large motor on questionable electrical capacity...by ramping slowly, your peak starting current is significantly less. The electronic brake is cool too, as it can slow things down very rapidly (but controlled).

Spence