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Pancake Die Cutting Angle

The need for many small pieces of sheet cut the same way has rekindled my interest in making pancake dies. I reviewed a lot of what is in the archives, some of which I was a part of, but I can’t find a reference to how to calculate the cutting angle. After doing a lot of drawing and resurrecting my now nearly 60 year old knowledge of geometry and trigonometry, I think that it is as simple as calculating the decimal value of the width of the cutting blade divided by the width of the die stock and looking that value up on a sine table. This calculation comes close to what I find on different tables that show the cutting angle for different blade size and die stock width combinations. I think that there are fudge factors for soft vs. tool steel and weather or not the die will be hardened, but my calculations are close. I find a lot of phone apps that will display the angle of a surface away from level. This is an easy way to set my adjustable bench pin to the right cutting angle. Can anyone confirm this calculation is correct or tell me where my memory and/or logic has failed? Thanks…Rob

On page 15, there is an illustration of gauges and angles, but no formulae. https://silversmithblogdotcom.files.wordpress.com/2014/05/project-report-no-12e_1-the-r-t-blanking-system-may-1980.pdf

I really should have had a cup of coffee before I tried to respond to this. I’ve forgotten all of my trig formulas too, so I had to look this up. Since we have the side and the opposite, I believe we need to use the inverse tangent function to determine the angle of the hypotenuse. I found this page to help me understand, rather than pull out the old geometry books! https://www.mathsisfun.com/algebra/trig-finding-angle-right-triangle.html

I am just drinking my coffee now, I hope that you got yours. Thanks for your very helpful reply. I am retired and spend all together too much time trying to figure things out. This is a real challenge for me if it requires that I recall, what is for me, very old math information. I will review the RT blanking information and see what it has to tell me. In the end, I can cut out dies that work for me, I am just trying to figure out how an why they work. thanks again…Rob

I just read some earlier post where it was explained that the cutting angle is a function of the width of the saw blade and the width of the material that is being cut. These two dimensions are the length of two sides of a right triangle. Using basic trigonometry, you can calculate the sawing angle. I notice that adjustments are made for tool vs. mild steel and whether or not the die will be heat treated. This answers my original question. After cutting a number of practice dies and going through all of my 3/0 blades, I left with two questions. What is the best blade to buy by the gross and is there a minimum size cut angle where the die won’t be able to support itself. Attached should be a picture of my latest practice die with an arrow pointing to the area that is a problem. I am using 18 gauge mild steel. There isn’t enough metal to support a cutting edge. Any suggestions are appreciated…Rob

This should read 16 gauge, not 18 gauge. I originally started with 18 gauge, but bought 16 gauge from my local welding shop.

hi,
did you run across this blog post by dar shelton of sheltech…has some interesting info

http://userblogs.ganoksin.com/sheltech/2018/03/10/real-pancakert-die-real-pancake-die/

julie

I can’t open the link, but I have read a lot of what Dar, Kevin Potter and others have written. There is a lot, especially from 10+ years ago. I have discovered that, at least for me, creating a design first and then trying to cut it out is the way to go. Successes and failures will help me figure this out. In the end I am just trying to add blanking dies to my tool box of knowledge and experience. I do need to buy a lot of blades because I am going through them. Thanks…Rob

hi,
ok
perhaps you could just search it in web
“A brief history of rt pancake die universe”

image|231x500

lots of diagrams re angles…

julie

Found it, thanks!..Rob

hi,
were you able to copy/paste this link, that was noted in the blog?

very technical

(or could type it into web search)

julie

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I was, thank you…Rob

i experimented a bit with these back in the '90’s. A clever friend created a jig with an attached saw frame that could be adjusted to the correct angle. all you have to do is use the c-clamp to attach to a table, insert your steel (with a pre-drilled hole for the saw blade) and saw away. the adjustable ‘table’ of the contraption takes care of the need for consistency of the angle. I will try to add a photo I would love to sell this along with some of the steel. if you are interested email me: bbbsimon@comcast.net

i experimented a bit with these back in the '90’s. A clever friend created a jig with an attached saw frame that could be adjusted to the correct angle. all you have to do is use the c-clamp to attach to a table, insert your steel (with a pre-drilled hole for the saw blade) and saw away. the adjustable ‘table’ of the contraption takes care of the need for consistency of the angle. I will try to add a photo I would love to sell this along with some of the steel. if you are interested email me: bbbsimon@comcast.net

1 Like