Handy dandy pulley calculator.

[websterz]

http://www.forestryforum.com/members/donp/pulleycalc.htm

I am building a power hacksaw and needed to calculate the jackshaft numbers needed to reduce a 1750 RPM motor down to 60-70 RPM. You can do this easily by putting in the first set of numbers, in my case a 2.125" drive pulley running at 1750 RPM driving an 11" sheave. This gives me 338 RPM. By re-inputting the new speed and leaving the pulleys the same I can see the effect of  a jackshaft assembly consisting of a 2.125" to 11" pair, driving a second 2.125" to 11" pair on a 1750 RPM motor. I end up with 65 RPM. Just where I want it. Hope this link helps someone. 

[tinkerer]

Hey Websterz,
The calculator is cool, but it won't do me any good until you put up a tutorial with pics on how you are building your power hacksaw.
Seriously, How do you deal with the feed rate through the material and all of the other things i will need to know.

[websterz]

Here ya' go:

http://www.vintageprojects.com/machine-shop/power-hackSaw.pdf

[tinkerer]

Cool beans buddy. That looks easy enough. Thanks.

[fluxcored]

Hi Guys,

How's it going with the power saw building? I started in October and am still not even close to finishing.

I've turned the shafts and rebushed pulleys for the primary drive shafts and although my efforts will not win first prize, I'm happy with the outcome thus far. I just finished a cam this weekend to provide a lifting action and possibly drive a coolant pump.

I suspect that the motor I have will be too puny too drive this contraption.

I figure on making the slide bar and saw frame next so that I can see where the secondary drive shaft and crank should go. Besides I'm all out of cash for bearings for the secondary shaft.

All odds are against the saw working first time around as I'm just winging it but it's a lot of fun, let me tell you, and I'm not going to mind fixing and improving on it.

Hope you guys are doing better than I am.

[tinkerer]

I am ashamed to admit that I haven't even started. I thought I would have all kinds of time on my hands when I retired, but I got involved in so many things, the only time I get in the shop is when I make something for someone else. The lathe hasn't been turned on in a couple of months. Neighbors kid is having a baby and he wanted to build a crib, so I am assisting him in that, not doing it for him. Another friend bought a combo machine and  needs help installing and learning how to operate, so I am helping with that. Booster club is crazy busy and the church takes the rest of the time.

[websterz]

I have built my saw a dozen different ways in my head but it still isn't cutting right. I'm thinking about scrapping it and rethinking ...

[fluxcored]

Tinkerer, do'nt sweat it. My projects' are always behind schedule + I find that I'm lucky if can spend 6 hours a week on the lathe. So I'm really learning at a very very slow pace.

I've always got a backlog and now that I have a lathe it's even worse because I'm starting to build tools to make tools to make a particular part for some project I've got going.

Websterz, I'm mentally prepared that when I start up mine it's going to fall apart!! If it manages to survive it's definitely going to be extremely noisy.

Any case guys, good luck.

[ViKARLL]

I just finished a cam this weekend to provide a lifting action and possibly drive a coolant pump.

Hi fluxcored,

I am in the process of building a power hacksaw. I have surfed fruitlessly for nearly a month and was about to give up when I came across SMF through your post, mentioning about a cam lift mechanism of the blade on the return stroke.
Many people elsewhere have touched this topic but you are the only one who stated making one himself. Others are either vague about it or sounds that it is so trivial. I have never seen the anatomy of a power hacksaw so I am lost.
Could you please educate me on how this cam mechanism exactly works, where is it mounted etc., If you can kindly offer some sketch / picture, that would be great.
I know it is one generation late to write to this thread but I thought I'll give it one last shot.

Thanking you in advance with best regards,