Dunlap/craftsman band saw

[mickri]

Saw this band saw on CL https://slo.craigslist.org/tls/d/band-saw/6643061250.html It has been for sale for a while.
I did some research on this model and seems like it might be a good addition to my shop. The drive motor sits underneath the saw and the drive pulley is on the outside. This makes it relatively easy to change the pulleys to slow the speed down for metal cutting. Found a couple of sites online where people showed how they had made a multiple pulley set up to be able to quickly change from wood cutting to metal cutting and vice versa.
Anybody have one these and what do you think.

 

[FOMOGO]

That is a very nice saw. Do you know the speed range it has presently? A gear reduction unit is one way to go for metal speeds. $75, I'd be ecstatic. Mike

 

[mickri]

I don't know the pulley sizes on this particular saw. This saw has a 1750 rpm motor. From what I found online at vintagemachinery.org this saw with a 1750 rpm motor had a 2" drive pulley on the motor and a 5" driven pulley on the saw. If I did the math right that would give 700 rpm at the saw. Some of these saws came with a 10" pulley on the saw which would give 350 rpm at the saw. In my online research I found people who had cut the speed down to the 100 to 200 rpm range for metal cutting.

 

[Nogoingback]

At $75.00 you have some headroom on cost. An 1140 RPM motor (6 pole, I think), would help get you down into the speed range you need.
I got an NOS motor like that for my drill press off of ebay for about 50% of list. With a new motor and some different pulleys you might
get what you need.

Nice saw.

 

[mickri]

On my way back from my Mom's 100th birthday party I was able to stop buy and look at this band saw. I bought it for $75.
The seller bought it about 15 years ago for $50. No stand or motor and it needed a complete restoration. He replaced everything that needed replacing. Bought a 1750 rpm motor and built the stand. There is a 5" pulley on the saw. The motor pulley is a combination pulley with I believe 2", 3" and 4" pulleys. I did not measure them. The motor is on a hinged sliding bracket and it is easy to switch the belt to get different speeds. It runs smooth and quiet. Seller told me he rarely used it and got tired of it taking up room in his garage shop. The current speed range is for wood cutting. Seller never used it to cut metal. Came with a couple of wood cutting blades.

I will get a metal blade for it and replace the 5" pulley with the biggest pulley that will fit on the saw. Hopefully that will slow it down enough to cut metal. If not I will add a combo pulley.

Had to take it apart to get it into my truck and haven't unloaded it yet. And I need to figure out where I am going to put it in the garage. I'll take some pictures once I get it out of the truck and put back together.

 

[CluelessNewB]

The Vintage Machinery site has a bandsaw calculator. You enter your motor speed, driving pulley, driven pulley and wheel diameter and it will give you surface feet per minute: http://vintagemachinery.org/math/sfpm.aspx

With a 10" pulley and a 2" pulley on the motor you might be ok for aluminum but way too fast for steel, brass or cast iron.

As a reference point the 14" Delta Wood/Metal Bandsaw had a reduction gear box. The metal cuttings speeds ranged from 40 to 335 SFPM. The wood cutting speed was 3000 SFPM.

 

[mickri]

Been researching cutting speeds and how to achieve the correct speeds for metal. Also looked into band saw blades. A big thanks to CluelessNewB for the link to calculate sfpm. That was a big help.
I will be getting a 10" pulley to go onto the saw. I will combine a 5" pulley with a 1.5" pulley for speed reduction. The gear train will be 1.5" on the motor driving a 5"/1.5" combo to a 10" on the saw. If I did the math right and with the help of the link to calculate sfpm I should end up with 268 sfpm. My research on sfpm for mild steel indicated a sfpm around 250. The cost of the pulleys and assorted bits and pieces will run me about $50 plus the cost of the saw blade. I plan to buy both a wood blade and a metal blade. I haven't figured out what I will need for wood cutting. That is where I am at with this right now. No rush to get it done.

 

[CluelessNewB]

Your calculations seem about right. I would be a bit concerned about the small 1.5" pulley and belt slippage especially on the second one driving the 10".

 

[CluelessNewB]

P.S. You might want to consider using roller chain drive for the last stage driving the saw. There would be no slippage and getting a 6.54:1 reduction would take up less space. (72 tooth on saw driven by 11 tooth). My Dad did this on an old Walker Turner 14" saw back when I was a kid. He later used a gear reduction box he acquired, I believe it was about 20:1 but I'm not 100% sure, it was back in the early 70's.

 

[mickri]

Hi Clueless,
Just saw your post. Don't know how I missed it. Thanks for the suggestion about using a chain drive. Discovered that electric bikes have sprockets up to 90 teeth. The sprockets off of an old 10 speed bike is another possibility. Their biggest size is 52 teeth. Lots to think about.