Make-your-own blades?

[Query]

I'd like some feedback, from people with a shop or engineering background on whether ordinary people could make their own blades to try many shapes.

Given a sufficient sufficient number of blade tracings and measurements of various blade types and sizes to work from, I could write a simple computer program (not hard - I used to write image processing software) that would create an image of the runners that could be printed on label (adhesive backed) paper, with outline shape and hole positions.

The program would input user-provided parameters - length & radius of main & spin rockers, position info for the ball of the feet, approximate height over the ice of the toe and heel. Angles, sizes and heights over the ice related to the toe picks.

Stick it onto soft sheet steel, clamp in place to a big piece of particle board or plywood, drill holes with a drill press or hand-held drill+drill guide, cut with a jig saw. Smooth and add a hollow, use hand tools like Pro-Filer, but start with a coarser stone than Pro-Filer comes with for speed.

The chassis could be a simple aluminum mounting plate, cut to match another image, with bolted on (strong) drilled right angle steel brackets. The runners would fit between them, with thin gaskets to allow for play. (Or possibly different width gaskets, to adjust runner offset.) Probably a bit heavier than commercial blades and chassis, because the design is crude. Probably separate mounts for runner and toe pick to speed experimentation.

Once you've decided on the right shape, soft steel would wear out fast. Could most people harden and temper edges with a propane torch, thermometer and oil? Or would we need to hire a blacksmith?

Is commercially available soft steel plate is available in the right thicknesses, and would it be smooth enough?

We would also need to make wedge shims between the mounting plate, to further adjust blade height, and because boot bottoms aren't co-planar, and they would need to be sanded to fit your boots. Cut from rubber hockey pucks.

So?

[Kaitsu]

Query,

Today there is much more modern ways to cut steel than jig saw. If you can write programs which creates runner profiles if you give following parameters.

* Blade size
* Main rocker radius
* Amount of spinning rockers 1 or 2
* Spinning rockers radiuses
* spinning rockers start and end point distances

Ill promise to continue from that, your your program can create file which can be imported to the Autocad CAD software. You can start from these profiles => https://cdn11.bigcommerce.com/s-u1ecyriv/images/stencil/1280x1280/products/3099/4782/paraCP-3__05219.1580504904.jpg?c=2

Smooth intersection points between different radiuses has been difficult to me, when I have tried to model blades profiles. Its less or more pure math, but I am not so good in that. If some one can guide how to do it in Autocad, advices are very welcome.

[Query]

I picked a jig saw and drill because they are cheap, but I'm not sure we can cut & drill accurately enough - 2 or 3 thousands of an inch profile difference near the main/spin rocker transition affects how I skate a lot, though I don't understand why, and whether that is true for other skaters. I hoped to use abrasive stones to even out the rough cut, but am not sure that would work. I doubt most of us could afford computer guided cutting and drilling machines with that accuracy.

Could you use a computer guided cutting and drilling machine to make them for us? Is yours that accurate? What would you charge per blade pair, and what are shipping costs to the U.S.? I'd like to try many shapes.

I don't know if runners squeezed between gaskets or washers by nuts and bolts would be stable enough for good skating. And whether cheap readily available right angle steel bend pieces are strong and accurate enough to be right angle brackets. Or I personally already have Ultima Matrix 1 chassis - perhaps you could just cut runners that fit them, though most skaters would have trouble finding them.

Some blades shapes may have design patents... Of course, patents might be a source of more accurate drawings too.

I don't know anything about autocad formats. I tried to look autocad *.dxf file formats up. Extremely complicated, and would be hard to do. Could you work from images? E.g., *.tif images can include scaling info, and it's a very simple format to create. I could create *.tif black & white of outlines to cut, with marked hole drill positions.

I found free utilities to convert *.tif images to autocad DXF files, but don't know if you could use that result.

The math isn't hard. For a smooth transition, the two circular arcs have the same tangent (i.e., slope). E.g., for a horizontal slope, paste two circular arcs that are cut vertically together. A horizontal slope at the intersection probably isn't best. So I could include many mounting holes to try different slopes and mounting heights. And other to mount a separate toe pick pieces, also with with many holes to get different heights and slants.

I think your linked image was drawn by Paramount and is inaccurate on MK and JW blades - but might be a good starting point...

[Kaitsu]

Query,
Kindly draw me a sketch which explains these tangents, horizontal slopes etc.

[Query]

I have temporally placed a compressed folder with all the listed files at
http://mgrunes.com/boots/ToKaitsu.zip

Look at ToKaitsu.rtf for an expanded version of this post.

WilsonbladeRadius.jpg is an old (2014?) diagram showing typical MK and JW blade main and spin rocker radii, from 2014, or maybe earlier, that I found on the Internet. It does not agree with Paramount's drawings, like the ones you posted. Interpret that as you will.

I use rocker.png (also at http://mgrunes.com/boots/rocker.png) to measure blade rocker radius. It contains embedded scaling info. If your printing app prints it at the right scale, the dark horizontal lines should be 1 USA legal standard inch (2.54 cm) apart, and the light horizontal lines should be 1/4" apart. (Note: not everyone uses the same "inch", not even in the USA. E.g., Finland used substantially smaller inches. A good reason to use the metric system?)

But the detail level is only about 600 dots/inch, not good enough for production purposes, but good enough to explain what I mean. I think I produced it from postscript file idl.ps, which I think I created at 2540 dots/inch, using my IDL language program rockerprofiles.pro.

At the vertical center the (curved) rocker profiles are vertical (straight up and down). So a tangent line drawn against them would also be vertical.

I have cropped portions of the 7' and 9" radii curves near that center, and rotated them 90 degrees so the curves are tangent to a horizontal line, in files 7foot.png and 9inch.png. (At this scale, the 7foot.png curve is effectively a horizontal line, because the resolution isn't high enough to tell the difference, so the 7' curve IS effectively a tangent line. )

I sort of joined the two images together to produce sweetspot.png, and added a red tangent line, which is horizontal. The vertical line at the join point is part of the radius line for both curves. The place where the two dark joined curve is what I was taught to call the "sweet spot" (the point at which the main and spin rocker curves join) in a blade produced with 7' main rocker and 9" spin rocker.

I have labeled the main rocker, spin rocker and tangent line in sweetspot2.png.

[Query]

In retrospect the diagram was a bit unclear.

Different skaters and coaches disagree on what part of the blade you are skate on during one foot glides. Some say that you should skate on what I call the "sweet spot".

1. If you ignore the fact that the blade digs into the ice, there is a single point of contact between the blade & the ice, and the blade is horizontal at the point of contact. So, if you skate on what I call the sweet spot, the bottom of the blade there, the tangent line, and the ice surface, would all be the same, and are all horizontal.

I drew the tangent line slightly below the curve that is the bottom of the blade, so you could see both.

2. I only mean "horizontal", in a forwards/backwards tilt sense. But most of the time we are on an inside or outside edge, so the blade has a sideways tilt, which I ignore here.

3. Another way to look at this is to think of radius lines instead of tangent lines.

On every part of a circle (or circular arc), the radius line segment is at right angles to the circle. (Also to the tangent line at each point, which approximates the circle at points very close to the radius line.) By "radius line" I mean the line that contains the radius line segment, which is the line segment between the center of the circle and the circle itself.

At the sweet spot, the tangent lines for the main and spin rocker curves are the same. So the radius lines to both are the same. Skating there, both are vertical in a forwards/backwards tilt sense.

I hope that is clear.

[Kaitsu]

Thanx Query! You gave me a one piece to my puzzle that I have been looking for years. It took some time to understand the tangent thing you explained, but I believe that I know now hot it works.
Do you know the source of these JW and MK profiles you shared?

Can you give some specification to the blades you would be interested, so that I can start to sketch something?

* Blade size, example 10"
* Blade profile total length. Curve which starts right after drack pick (cross cut area) and ends to furthest point of the tail. 
* Which toe pick pattern? (I can draw cross cut, but only straight cut picks can be produced with laser or water-jet cutting.
* How many spinning rockers, one or two?
* Spinning rocker(s) lengths and radiuses
* Target for touch point length
* Target for heel lift height

With these information's I am able to draw something in CAD without your code.

[Query]

I've written a Fortran program that creates Postscript of the bottom profile of the blade, with toepick, but haven't tested it yet, cuz I need to get ghostscript running to see the output. It will take me a bit of time to fully debug it.

Perhaps you could extract the values your app needs from it, once I have it working.

What about the hardware that you have - what does it take and do? Can it cut, drill, and mill (making both sides of the cut piece the parallel to get a desired thickness near the edge) according to instructions? Is that common in machine shops?

Given that I want to play with many shapes, it might not make sense to go through you long distance.

I could get access to a machine shop on the Eastern shore of Maryland, by joining a club, but then I'd have to learn how to use it. Supposedly they offer lessons. But I'm not sure how much knowledge they a assume.

But I wonder whether a jig saw would be good enough...

And what about the idea of using a torch and hot oil to harden and temper steel (e.g., eventually 440C alloy)? Is it reasonably easy? Or would I need a blacksmith?

[Query]

I cannot find where I got the WilsonbladeRadius.JPG image. And it's probably somewhat out of date. Note that the position of the sweet spots is often changed by expert skate techs, to be close to underneath the ball of the foot. Not also that some people who say this are saying the entire spin rocker should be under the ball of the foot. There is no standardization of terminology or technique.

https://scarletskater.wordpress.com/2017/06/01/choosing-figure-skating-blades/
https://scarletskater.wordpress.com/2017/06/01/choosing-figure-skating-blades/
https://scarletskater.wordpress.com/2017/06/02/blade-profiles/

Note: these say many MK blades have 27" - not the 24" the image I found claimed.

https://figureskatingstore.com/blade-type-information/

https://ice-blog.riedellskates.com/know-toe-picks/ - says that spin rocker (what I call the sweet spot) should be slightly behind the ball of the foot. Many other people say it should be directly under, or slightly ahead of the ball.

https://www.afterness.com/skating/blade_rocker_measurements.html (Bill_s on this forum)

[Query]

I have slightly expanded that

http://mgrunes.com/boots/ToKaitsu.zip

folder.


It now also contains:
DrawBlade.f90     My current attempt at a program to draw Postscript blade profile.
DrawBlade.txt      Parameter file for a sample run. My program can input this,
                          or prepare parameter files and outputs for any chosen dimensions
                          and toepick angles. I admit I haven't fully verified it is correct.
                          Note that this is not any particular blade, but was just a test run.
                          I used .5 factor scaling, because I haven't yet figured out how to make it work in landscape mode,
                          and couldn't fit the sample blade on an 8.5 by 11 inch page. But there are photocopiers that can
                          double the size of the output image. It is a text file.
DrawBlade.ps       The output postscript file. It is a somewhat human readable text file.
typescript            The program dialog that occurred while running that program. As you can see, it has text dialog,
                          not a graphical user interface.                         
DrawBlade.png     A PNG format image prepared from that, by an old version of Paintshop Pro. I selected 600 dpi
                           resolution, though paintshop can also do 1200 dpi.

[Query]

I've spent more time at this than I originally thought. I'm fixing some issues on that program right now:
1. I am creating a diagram that explains the input parameters.
2. I didn't take into account the width of the lines. In particular if I try to cut with a jig saw on the outside (rather than the center) of the printed lines, that would distort the shape, especially of the toe picks. Perhaps the suggested line width should be adjusted too.
3. I don't know how and if CAD programs deal with that - whether, when inputing Postscript, and/or images, they take that into account, when creating computer guided cutting and drilling instructions.
4. I can't afford AutoCAD, but there are free CAD programs I could play with that could maybe teach me how they are used. The ones I have looked up on the web so far can't take in postscript. But some of them might take in PDFs - and there are free tools to convert Postscript to PDF.
5. Likewise, a CAD program would need to take into account the width of the cutting tool. Again, I don't know if CAD programs take that into account.
6. I need an option to extend the cut lines at toepick corners, so I can cut them more accurately. And I don't know whether CAD programs do that either.
7. None of the tools I have found so far to convert Postscript to images correctly produce image more than 8.5"*11". So I scale down by a factor of two. Needs to be fixed. Or I need to print at a diagonal, and/or split the diagram in two, with clear marked points to tape the printed pages together. And/or to fix rotation, so the blade can be printed at a page diagonal. And/or, I produce my own scaled TIFF image, instead of Postscript.
8. I need to adjust the way lines at angles join together better. I though "butting" was best, because it is Postscript default but the corners look wrong.
9. I need to check that my pick angle calculations are right.
10. I need to add the rest of the runner to the diagram, and maybe produce one for the mounting chassis. And add countersunk mounting holes.

Some of these may be fixed within a few days. But learning about CAD programs will take longer. Sorry for the delay.

[Kaitsu]

Thank you Query, I can see you have used lots of efforts to make your code. Unfortunately it seems it does not help me so much. Blade profiles which are in picture format are basically same as pencil tracings what I have from the different blades. Its not so easy to copy profiles by trying to overlay lines in CAD software. I can measure example radiuses of the blade with some accuracy, but not as accurately as I would like. Even bigger problem is define the point where radiuses changes. I will try to 3D print my own rocker radius gauge during the weekend. It uses ball bearings and measures radiuses from the edges of the blade, not from the hollow like Sid Broadbent tool does. Otherwise working principle is very similar. I hope it helps to measure profile radiuses more accurately so that I would have more clear overview from the different blades. If I can measure length of radiuses and radius it selves, rest is quite easy.

Attached file where you can see sketches where one is made with your instructions and using the Paramount skates profile data. In the next page you can see sketch where I have overlaid profile which I have made from the pencil tracing and profile which I made based on your instructions.

I will make 3D model from some blade profile as soon as I have time for that. It takes some time. I have planned to print also profiles kind a mirrored so that I have gauge what to put on top of blade profile to see if theory meets measured / informed profiles. 3D printer is super nice invention and gives me lots of opportunities to make what I need. 3D printed blade profile would be much more accurate template to make own blade than jig saw. You could use example wood router which follows this printed template. You will hear more about this later. At the moment I am focusing more to get 3D model / print from the one complete blade.

[Query]

I'm still doing it for me.

Several CAD programs can input Postscript or PDF files (PDF files are easily derived from Postscript files - in fact I've done it.)

It turns out I made some algebraic errors in that code, concerning Toepick angles. I'm fixing that.

Also, looking at various photographs and tracings of blade profiles, it appears that all the blades I've looked at that have 3 rocker segments (i.e., 2 sweet spots in my terminology), when you rest on the forward sweet spot (which makes that spot horizontal), the drag pick touches.

So! It appears the forward sweet spot on such blades is specifically designed for scratch spins, and turns that engage the toe pick (like many people say to do in 3 turns). That is something I never understood before trying to write this code. (BTW I use 2 rocker segment blades, not 3 segment blades.)

I guess the back sweet spot is mostly designed for non-scratch spins?...

[Kaitsu]

Your post scrip file (profile) sees to be built from the very limited amount of lines instead of curves. Not sure if the problem is in post scrip translation when I import it to CAD or low resolution of your post scrip code. Or is this tracing from your jiw saw cutting 

I am still puzzling where the main rocker ends and where spinning rocker start. Where is the centre of the blade profile and is main rocker somehow longer either side of the blade centre point. This is not so simple. Your tangent explanation solved one of my problems, but I am stuck again in the same problem than in the past. My profile arcs does have now smooth joints, but still lots of things is unclear.

[Query]

The resolution is not specified in the PostScript code - postscript works with about 8-9 significant digits. And I added comment lines

E.g.,

72.0000000 72.0000000 scale

says that the units of measurement are 72 times the default postscript "points" (1/72 inch) measurement - so units are in inches.

Lines starting with % are comments, and can be ignored. E.g.,
% ***Rocker Segment 3 Radius=12.0000000 inches, curved length=1.20000005***

Circular Arcs use the "arc" operator:
0.832904458 12.0231428 12.0000000 -86.8169022 -81.0873260 arc

says to draw an arc centered at x=0.832904458 y=12.0231428, with radius=12.0000000, at angles from -86.8169022 to -81.0873260 degrees counterclockwise from the positive x direction. "-" means that it is clockwise from that direction.

Again, comments like

% ***ToePick #1 from back***
% *Angle to back of tooth=140.000000 Length=0.250000000*

can be ignored.

2.90614676 0.389485806E-1 lineto

("moveto" instead of "lineto would mean to move without drawing - or in this case cutting.)

says to draw a line from the current position (at the end of that arc) to

x=2.90614676 y=0.389485806E-1

But like I said, I did the algebra wrong on the toepicks, though I think I've fixed that.

Also, I guess a computer guided cutting tool needs to be directed to cut outside the boundaries of the object, which I haven't done yet. Or can the CAD program be told to do that?

I guess the cut lines still need to be extended a little past the object, or the object might not fully detach. Does the CAD program automatically do that?

Can the same computer guided tool also drill the holes at accurate positions, using a countersunk drill bit? And could it be told to mill the sides of the blade around the edges to the right thickness, and do it in a way that the sides are parallel?

Though maybe the milling can be guided by hand, since it doesn't need to extend exactly the same amount from different parts of the edge to be functional?

If the computer guided cutting tool uses a blade to cut, I assume the steel plate can't be hardened? Plus, the part that isn't near the edge should be tempered more, so it isn't brittle. Is hardening and tempering something that ordinary metal shops, like those that cater to automotive mechanics, can do?

[Query]

I have somewhat updated my DrawBlade program and related stuff. Some of it has been renamed or move. The new version is at

http://mgrunes.com/boots/DrawBlade

Note that DrawBlade.txt and DrawBlade.ps are much more readable. And my particular terminology (which tstop4me insists is not the standard he likes) that the program uses is explained at http://mgrunes.com/boots/DrawBlade/DrawBlade_labeled.png - The image can easily be viewed with a web browser. Most web browsers can use the mouse wheel to zoom in and out to see small text.

BTW, I know many people think Fortran is out of date (and to some extent it has evolved to meet a specialized market, supercomputing using massively parallel processors like nVideo graphics chips, where it is still by a small margin the most common language - though this program doesn't fit that criteria), and it is possible you have never heard of it, but Fortran compilers are available for free, such as "gfortran", which can be loaded in Cygwin and Linux.

[Query]

I would need about 1/8" (11 guage) 440C stainless steel for the final runners. About $90. Early prototypes could use cheaper steel.

I would need a heavy duty (over 600 watt) jig saw, and cutting oil. My best saw is borderline.

A $40 circular cutting jig would make smoother arc cuts than I could. But wouldn't do 18" - 8 foot radius. I could maybe tape on a long flat extension piece. The resulting offset would make the arc imperfect. Wouldn't matter much for 7 or 8' radius arc. Might matter for an 18"-27" radii segment.

Could use the radial lines my software can generate to get the direction of the center of the arc right.

Extruded aluminum channels (with a right angle bend) might be the simplest right angle brackets that could be bolted onto the mounting plate.

I could add free software to generate DXF files for CAD/CAM. (For that matter, I could have used free Postscript generating software, but I didn't know it was available.) And maybe FreeCAD could generate the CAM files to control a CNC guided milling machine, which could both mill (to cut) and drill. But CNC milling machines are expensive and apparently easy to break. So maybe not worth it.

A milling machine might be needed to thin the runner at the bottom.

I'm getting discouraged.

[Query]

A few more thoughts:
1. It would be fairly easy to modify DrawBlades.f90 to extend the cuts, and compensate for line width so one could cut on the outside of the line, because the runner is a simple convex shape.
2. Where a long radius arc and a short radius arc meet, one would cut and extend the long radius arc first, then cut the short radius arc.
3. Just as a circle cutting jig would help make much cleaner rocker arc cuts, a strip cutting jig would help make cleaner straight line straight line cuts. I already have one.
4. One could make one's own circle cutting jig as a thin board of sufficient length, with an attached metal strip that fits into the same slot as the strip cutting jig, and nails at the right radii. The nails would fit into boards, mounted onto separate tables at the same height as the board and table the steel was clamped to.
5. Hardening 440C steel sounds complicated. Hard to make sure it doesn't warp? Temperature by color good enough? 6. A propane torch is more than hot enough - have to make sure the steel doesn't melt. On the other hand, if one actually austentizes it, it would be non-magnetic, so steel filings wouldn't stick during sharpening.
7. Sheet/bar 440C steel is listed at about Rockwell hardness 20. The main body would presumably stay that hardness. Is that about right?
8. Maybe Jerry's ISE blades are cheap enough to use instead of all this effort... Like I said, I'm getting discouraged.

[Query]

Oh. The guidelines for one of the skate forums I use say the rules for links to external sites must be

Links to established news sites
Links to Youtube, Instagram, X, and Facebook
Links to non-commercial personal sites, blogs, channels, etc. are only permitted in the Share It forum as long as there is a reciprocal link.

My personal website isn't commercial:, but that might change, and it links to commercial sites. My Facebook page still has stuff from when I ran a math tutoring business. And Before sites verified email, evil people opened accounts at the other major social media sites, giving my email address.

If I post Postscript for my generated images, many people don't have GhostView or equivalent to read it. And you need the assumed paper size so GhostView displays and prints it right. Plus my current programs print long versions of numbers for accuracy and alignment, using Fortran g0 and i0 formats, so my postscript files are long. I could shorten them for posting... But Skatingforums lets me add the actual images, though that's a bit dangerous - some image formats can embed malicious code.

Am I using the wrong reference points? My "sweet spots" are where rocker curvature changes. I've been placing the sweet spot (the back one if there are 2) horizontal on my output horizontal, because some say that is where you  turn and spin. I find it by seeing where the blade or its tracing departs my rocker curves, but its hard to be accurate.

It's much easier to measure what I call the "modified sweet spot" - the point on the blade where the toe pick starts to touch on a rigid surface. Some say that is where you turn and (scratch) spin. (But AFAICT, when 3 rocker segment JW blades are new, the modified sweet spot IS the forward sweet spot.)

Some expert skate techs modify blades so one or the other of these sweet spots is radially projected to the center of the ball of the foot, which in turn, should be the place where the upward bend of the footbed is centered, for foot health and to prevent sliding.

But every sharpening, the modified sweet spot moves back a fair bit, unless you trim the back toepick tooth enough to keep it stable. Should expert sharpeners do that?

I still need my version of "sweet spots" (and rocker radii) to define and draw the shape of the blade. But if I switch to "modified sweet spots", inaccuracy won't matter as much.

[Query]

I don't yet measure the relative height and forward position of the mounting plate, but that's very Important. AFAICT, on a full custom boot, the front and back of the outsole radially projects to the front and back of the foot. Skate techs try to place the front and if possible the back of blade mounting plate to match the outsole (makes little sense on non-custom boots!). So the "blade length", which is  measured from the mounting plates, is the radially projected foot length of the foot, or slightly shorter, on full custom boots. (True for all custom brands??)

Even within freestyle blades, the radially projected back toepick tooth projects to a part of the foot (or ahead of it) that depends on blade model. Interesting. (And which radial line direction should you use to measure that?)

Perhaps an expert sharpening should always trim the back back toe tooth in a way that continues to radially project to the center of the ball??

I've been told (is it true??) that the front parts of blades - all rocker radii, length of all but the main rocker segment - is the same for all blade lengths of given MK or JW model. It would means the lift height depends a lot on the blade length, and as feet grow, a given model would interact very differently with them in many ways.

E.g., "lift height" of the blade - the height of the blade back ("tail") when on the modified sweet spot, would change a lot with length. Is that true?