Author Topic: powered hacksaw (maybe)  (Read 166 times)

savarin

powered hacksaw (maybe)
« on: May 23, 2020, 04:31:40 AM »
I'm thinking of building a powered hack saw (not 100% certain but maybe)
 I've read the gingery version (bit flimsy in my opinion) watched plenty of youtube versions.
 A lot of them only use around 2" max stroke of the saw blade which seems to be a waste to me.So some questions
 what is the maximum length of stroke for a 12" saw blade?
 I'm thinking that if the saw almost touches the vice edge on the forward stroke then that vice edge almost reaches the middle of the blade on the back stroke then just short of half a saw blade length of material could be cut.
 Am I wrong in my thinking?

34_40

Re: powered hacksaw (maybe)
« Reply #1 on: May 23, 2020, 06:41:40 AM »
If you are going to make it yourself. Then make it with a variable stroke.  In a larger o.d. or width - you'll need a shorter stroke,  smaller o.d. / width then you can use a longer stroke.
Clausing 108, Clausing 8520, Atlas Horizontal, Lincoln stick and mig welders

savarin

Re: powered hacksaw (maybe)
« Reply #2 on: May 23, 2020, 07:00:45 AM »
so in effect you could cut something just slightly shorter than the blade length give or take some TPI

woodchucker

Re: powered hacksaw (maybe)
« Reply #3 on: May 23, 2020, 08:29:29 AM »
I have a small portable unit. I can lift it by hand. If you want, I'll take some pics. Is it great, no, but it does the job. I used it a few weeks ago to avoid sitting there cutting heavy flat bar.


I don't think it needs a longer stroke. I am not doing the work, so it's fine, yea it doesn't wear the blade fully with small cuts.  But I think a variable  unit might be more work than I want.  I would see a wheel with a bunch of threaded holes at different radii and a precision shouldered bolt with a locking nut. But I would just set it an leave it.



Jeff
Clausing 8520   SB Model 9a - power hacksaw, Milwaukee band saw in a table.  Delta Rockwell Surface Grinder (not online yet .. being rebuilt where am I going to stick this)
For pics: https://imgur.com/user/woodchucker/posts

Terrywerm

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Re: powered hacksaw (maybe)
« Reply #4 on: May 23, 2020, 09:58:23 AM »

I've got a large power hacksaw, a Keller 5HD.  It is listed as being 10.5" x 9" in size and has a 6" stroke.  On low speed it runs at 80 strokes per minute. It will handle blades up to 18" long, though currently I am using 14" blades in it. It does a great job but a 6" stroke takes some serious power when cutting larger pieces of stock. It has a 1 1/2 HP motor on it and if I accidentally set the cutting pressure too high she will slip the belt. A saw this size is usually overkill for shops like ours, but it is nice to be able to wrestle a chunk of 10" channel iron into it and make a nice cut on it. Oh, and the price was right - I got it for free.


For a benchtop saw using standard hacksaw blades, I would keep the stroke down around 3 or 4" or so, definitely not more.


For a variable stroke you could copy the variable stroke mechanism like many shapers have. I think it would be more work than it would be worth, however. The idea of having two or three different pin locations available on your crankwheel as Jeff mentioned may be the easier method to come up with a variable stroke.


Since power hacksaws are generally built for a certain maximum stock size, stroke will be limited by blade length.  Using a standard 12" blade, you lose about 2" right off the top for the amount of blade lost to the blade frame and for a bit of frame clearance in relation to stock.  If you then want to be able to cut 6" channel iron laying flat, you are left with a maximum 4" stroke.


Now if one is considering a lighter saw, with say a maximum stock size of 4" a stroke of 6" becomes mathematically possible, but the power requirements will increase as well. You could gear the saw drive a little deeper to gain some more power at the blade, but doing so will also make for a slower cutting speed.


Long story short, it's all a game of trade-offs. Figure out what specs are most important to you and go from there.



Terry

Making chips with old machines!

chips and more

Re: powered hacksaw (maybe)
« Reply #5 on: May 23, 2020, 12:28:27 PM »
I thought I was the power hack saw? With hack saw in hand. It’s portable, you can vary the stroke and take a break when needed. It’s great for small stuff, not so for bigger. Good exercise…maybe. Develops hand eye coordination…maybe. The price is right and easy to hang/store on a nail :))

woodchucker

Re: powered hacksaw (maybe)
« Reply #6 on: May 23, 2020, 01:10:31 PM »
Pics of the small benchtop model.
It's about 25-30 lbs
Jeff
Clausing 8520   SB Model 9a - power hacksaw, Milwaukee band saw in a table.  Delta Rockwell Surface Grinder (not online yet .. being rebuilt where am I going to stick this)
For pics: https://imgur.com/user/woodchucker/posts

f350ca

Re: powered hacksaw (maybe)
« Reply #7 on: May 23, 2020, 07:44:27 PM »
Ive thought about making one, more for the cool factor.
Could you not have the vice moveable to evenly wear the blade?
Also liked the adjustable stroke idea.
The weight on the blade should be relieved on the back stroke, thought that could be done if the crank was placed below the blade so it pulled down on the power stroke and pushed up on the return,

Greg

woodchucker

Re: powered hacksaw (maybe)
« Reply #8 on: May 23, 2020, 08:26:17 PM »
Greg, there's nothing cool about a power hacksaw.
If you have a horizontal bandsaw, you are in a better place.


I don't have one, nor do I have room for one. So the benchtop model works well.

Jeff
Clausing 8520   SB Model 9a - power hacksaw, Milwaukee band saw in a table.  Delta Rockwell Surface Grinder (not online yet .. being rebuilt where am I going to stick this)
For pics: https://imgur.com/user/woodchucker/posts

Terrywerm

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Re: powered hacksaw (maybe)
« Reply #9 on: May 24, 2020, 08:24:43 PM »

My power hacksaw is WAY cool. The various young folks that stop by here with their parents or grandparents all seem to think so too. They have no interest in the lathe or mills, but if that saw is pulled out and running they cannot seem to take their eyes off of it. Just to prove a point to my wife one day, I pulled it out on the driveway and did some cutting out there. It didn't take five minutes for the neighbor kids from both sides to come over just to watch.


One man's pleasure is another man's poison. For those who like the roundy-round band saws, that's fine, that's your choice. I might have to wait a little longer for my power hacksaw to complete a cut, but considering that this is a hobby, I've got all kinds of time. Besides, waiting for a cut to complete is the perfect time to sip a cuppa Joe.


 :coffee2:
Terry

Making chips with old machines!

woodchucker

Re: powered hacksaw (maybe)
« Reply #10 on: May 24, 2020, 09:01:05 PM »
I stand corrected Greg, Terry says it's cool, you think it's cool... I've never thought my little guy was cool.


I've got to show off my cool powered hacksaw and see if I can attract any hot looking women...  :)) :72:


LOL...
Jeff
Clausing 8520   SB Model 9a - power hacksaw, Milwaukee band saw in a table.  Delta Rockwell Surface Grinder (not online yet .. being rebuilt where am I going to stick this)
For pics: https://imgur.com/user/woodchucker/posts

Terrywerm

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Re: powered hacksaw (maybe)
« Reply #11 on: May 24, 2020, 09:16:58 PM »
I just came to realize that I am in this hobby for the wrong reason....     :57:
Terry

Making chips with old machines!

woodchucker

Re: powered hacksaw (maybe)
« Reply #12 on: May 25, 2020, 05:07:10 PM »
I was cutting a piece of steel today on the hacksaw.
My wife came out..
I said isn't this cool..


She said NO.


So much for cool :73:
Jeff
Clausing 8520   SB Model 9a - power hacksaw, Milwaukee band saw in a table.  Delta Rockwell Surface Grinder (not online yet .. being rebuilt where am I going to stick this)
For pics: https://imgur.com/user/woodchucker/posts

Terrywerm

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Re: powered hacksaw (maybe)
« Reply #13 on: May 25, 2020, 05:46:33 PM »
I was cutting a piece of steel today on the hacksaw.
My wife came out..
I said isn't this cool..


She said NO.


So much for cool :73:

Hmmm....   did you by chance have a poodle??    I don't think you did.

Having a little miniature poodle with you is the real trick. Women fall in love with itsy bitsy dogs. Once that happens, anything mechanical is cool. Heck, ANYTHING is cool then.


How do you think I get my wife to go with me to tractor / threshing shows and swap meets??   :72:


 :coffee2:
Terry

Making chips with old machines!

f350ca

Re: powered hacksaw (maybe)
« Reply #14 on: May 25, 2020, 07:41:41 PM »
Poodles don't cut it up here Terry. Now on the other hand Saddie is a true chick magnet. lol On a lease which she hates women are all over her, but pull up with her in the sidecar of the bike and its a stampede.

Greg