a dremel tool cutoff saw with a paper thin blade?

[Bob Blarney]

Hello,

 

While browsing, I saw this idea and thought it might be of interest to modelers.   During WWII, metal was not sawn with a toothed blade.  It was bandsawn by friction against the edge of a metal band that was moving at very high speed.  

You be the judge, and I suggest that you make a shield and/or wear safety glasses.  You might find the rest of the mag interesting too.

https://books.google.com/books?id=XCYDAAAAMBAJ&lpg=PP1&pg=PA229#v=onepage&q&f=true

[bruce d]

Thanks Bob, very interesting. The book opens to a page with a cut-off machine, is the bandsaw process you describe somewhere else in the book? Couldn't find it.

I used to read these every month, wish I had retained it all!

[vaddoc]

This looked interesting so i nipped out to the garage and tested it. 

I cut a circular piece of 60 grit sand paper and loaded it onto the Dremel. I tried cutting pear wood, I think 3 mm and brass, I think 0.8 mm.

At low speed it did not do well. At high speed the paper straightens and cuts wood very fast and cleanly. The surface of the wood that is at the grit side gets black and burned. The sand paper should last a long time but is dead easy to change. In all honesty, it seems to cut better than my proxxon table saw and is much safer as the paper just buckles and does not kick back.

With brass it did not fair well, it deviates and eats the metal

 

Turn down the volume, the video is a bit loud!

 

 

I am tempted to make a jig for the Dremel, it cuts wood well and is much safer.

[Bob Blarney]

On 1/18/2020 at 5:16 AM, bruce d said:

Thanks Bob, very interesting. The book opens to a page with a cut-off machine, is the bandsaw process you describe somewhere else in the book? Couldn't find it.

I used to read these every month, wish I had retained it all!

The bandsaw friction cutting method was described somewhere in a wartime issue - sorry, I don't remember which one.

 

Popular Mechanics and Popular Science are available online now - free to view and searchable within an issue or all issues.  Go here: 

 

https://books.google.com/books?id=ytoDAAAAMBAJ&lr=&rview=1&source=gbs_navlinks_s

 

and here:

 

https://books.google.com/books?id=wzsEAAAAMBAJ&as_pt=MAGAZINES&ei=QVtqTfSyLIf6zAThl82MBg&source=gbs_other_issues

Edited January 19, 2020 by Bob Blarney

[Bob Blarney]

Vaddoc,

 

Did you use two pieces of abrasive paper glued back to back as suggested?   I think it would be a good idea to determine the minimum speed of a particular grit, that will give a clean cut.  I'm not sure this is relevant, but when I sand woodturnings on my lathe, I keep the speed down to  400-700 rpm for workpieces 2-4 inches in diameter, so as to prevent clogging of the paper or actually melting the resin that retains the grit on the paper.  

 

And for metal, I wonder if silicon carbide autobody paper might be more suitable, although as I recall, brass is usually cut, turned, or drilled without lubricants.  But a lubricant might help..  Bacon grease is useful as a lubricant for cutting metals, and I've cut 1/8 aluminum on my scrollsaw using petroleum jelly as a lube. 
 

Edited January 20, 2020 by Bob Blarney

[vaddoc]

No, just threaded a single piece of sand paper. 

[bruce d]

2 hours ago, vaddoc said:

... it seems to cut better than my proxxon table saw and is much safer as the paper just buckles and does not kick back.

This is getting interesting.

[Bob Blarney]

Well, it seems this method is worth further evaluation.  Umm, how about trying a paper blade on the Proxxon?

 

[vaddoc]

should be doable, probably won't spin fast enough but I ll try it!

[Bob Blarney]

By the way, if you're experiencing kickbacks often, then I think you might need to review your technique.  Kickbacks occur when the wood is caught by teeth behind the apex of the cutting blade, is drawn into or away from the fence, and then it is picked up off the table and flung back towards the operator.   It may occur during a cut due to releasing invisible internal tension in the wood's grain structure such that it warps as it is being cut, but usually, a kickback is due to the operator choosing to cut 1) warped wood, 2) wood that has an irregular or curved edge against the fence, or 3) misalignment of the fence to the blade (i.e. they're not parallel). 

 

On small modelers' saws, a kickback may have unpleasant consequences, but I remember a 2"x6"x8' board that I cut on a 9 inch saw that was flung back and shattered against a wall behind me.  It was a sobering and thought provoking event, and has not been repeated.

Edited January 20, 2020 by Bob Blarney

[vaddoc]

Thanks Bob, I had not had one for some time but I do need to be extremely careful operating the table saw. What I liked about this is that it is very safe. Clearly it can cut wood very efficiently, I may play a bit with the idea.

[Bob Cleek]

20 hours ago, vaddoc said:

In all honesty, it seems to cut better than my proxxon table saw and is much safer as the paper just buckles and does not kick back.

Yeah, but don't forget the last paper cut you got!

 

[Bob Blarney]

3 hours ago, vaddoc said:

Thanks Bob, I had not had one for some time but I do need to be extremely careful operating the table saw. What I liked about this is that it is very safe. Clearly it can cut wood very efficiently, I may play a bit with the idea.

I didn't mean to be harsh.  

[vaddoc]

No worries at all Bob, your advice was very well taken! 

I consider my hugely underpower proxxon KS 230 table saw the most dangerous tool I own.