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Thread: Challenge 2020-21 Aussiephil
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15th September 2020, 12:23 PM #16SENIOR MEMBER
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Hi Steve, that would be absolutely wonderful and highly appreciated. I did read a couple of articles that said newer style commercial (i guess read cheaper) blades had straight edges.
From what i gather there are a number of key measurements. Lets see if i can list them.
Blade width at the top exit of the body.
Blade width at the bottom before the cutting bevel
Cutting edge length
Blade thickness at the top exit of the body
Blade thickness at the bottom before the cutting bevel
These should give all the required tapers ... I'd sort of expect the taper angles to be relatively consistent across different widths. if so then it becomes easy to have a dimension driven drawing in Fusion360
I'm still tossing up how to keep the high tech 3D materials approach and incorporate some timber inlay to gain some mass.
PS: i did 3D print the revised version and it looks a lot closer to images i have seen, just hadn't grabbed a photo of it yet
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15th September 2020 12:23 PM # ADSGoogle Adsense Advertisement
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15th September 2020, 12:45 PM #17
There should be a little clearance in the blade groove sides to allow some skew adjustment. This also prevents the blade from potentially splitting the dai at the sides where there is the least amount of material - speaking of wood that is (found out the hard way ).
Is your design going to allow for any adjustment to fit the blade? (ie., removal of material if the fit is too tight). I'm certainly curious to see your progress. I think you can say no one has tried this before.
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15th September 2020, 12:49 PM #18
Ok, no problem. It's getting late here, so I'll work on this tomorrow.
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15th September 2020, 01:26 PM #19SENIOR MEMBER
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The clearance to each side is allowed for at least in my head at the moment for the skew adjustment, easy to allow for in the initial 3D print, i just model the blade fractionally over size and use it to cut the base component in Fusion360.
As I do a lot of work in ABS the first version will be printed in that and it's actually really easy to work with all the normal wood working tools so fit adjustment should go well. the plan is to start around 0.1 to 0.2mm undersize and slowly adjust as per normal as ive seen methods.
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16th September 2020, 06:29 AM #20
IMG_0976.JPGIMG_4433.JPGIMG_0480.JPGIMG_1451.JPGIMG_1396.JPGIMG_2133.JPG
(pic 1) Selection of 65mm kanna. Basic shape/dimensions are within a couple of mm. All are flat top to bottom (pic 2). Most have some hollow side to side on what the Japanese would call the (omote) front (pic 3 - greatest, pic 4 - least [basically flat]). I think this hollow is more a feature of the laminated construction and heat treatment, and not necessary for function? Of course, there is some hollow on the cutting edge side (ura) to facilitate sharpening.
So using the kanna on the right in pic 1., which is new-old-stock and not been shortened due to sharpening (needs to be sharpened ), as representative of average measurements:
L = 115mm (97mm cutting edge to shoulder, where side meets top)
W = 67mm at the widest part, and 64mm at the cutting edge
T = 7mm thickest at the shoulder, 5.5mm at the beginning of the bevel
Chip-breaker width = 57mm. This will determine the width of the cutting edge and the width of the shaving exit.
Chip-breaker thickness = 5mm tapering to 3mm at the start of the primary bevel (pic 5). This taper is designed to be adjustable for fit by bending the "ears" (pic 6).
The thickness where the blade enters the dai is going to depend on the thickness of the dai and your blade angle. Most wood dai I have are 35mm (+/-). So that point equates to about 60mm from the cutting edge and in my example is 6mm thick.
Hope this helps. Sounds like you've got things well planned out.
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16th September 2020, 10:28 AM #21SENIOR MEMBER
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Thanks Sheets.
Yes definitely helpful all round and good to see the pics.
As part of the continued shared learning experience the curve you have noted is a individual makers design element and i quote from one of the tools from japan pages
You may notice a curious word there, kou meaning 'shell'. It does not mean that there is a shell in the blade, only that the shape of the blade represents a kind of shell. Contrary to it's appearance, there are very few straight lines in a kanna-ba, and most prominent is the slight curve across the width of the blade matched by the blade bed as well as the distinct hollow on the blade's back.
The very slight (and occasionally non-existent) width wise curve only really warrants acknowledgement here than an explanation. Regardless, the curve of the blade must be matched by the dai in the blade's bedding area as closely as possible to ensure good, vibration absorbing contact between the blade and body.
I'm going to guess this is a more common element/feature on blades used without a chipbreaker.
Cheers
Phil
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16th September 2020, 11:43 AM #22
Thanks for that tidbit of info - I did not know that. The anti-skew feature makes a lot of sense because the Japanese rarely add something that has no apparent purpose. I wouldn't think that the use of a chip-breaker would require any specific change or adaptation to the kanna-ba itself - merely a choice by the craftsperson and the dai drilled to accept one if required. Based on my collection (72mm as well), all with a chip-breaker except one have the hollow. So hollow seems more the rule than the exception.
Anyway, I planely am no expert, so there's lots for me to learn. Thanks for passing your findings on .
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16th September 2020, 01:37 PM #23
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16th September 2020, 01:47 PM #24SENIOR MEMBER
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16th September 2020, 02:23 PM #25
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16th September 2020, 03:52 PM #26
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16th September 2020, 04:23 PM #27SENIOR MEMBER
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Have you ever drawn something in humor then had a thought that it may be useful
With all the talk of aeroplanes with humor i had a little muck around in Fusion360 and added some wings onto the plane and then rendered it in red as it will go faster...
PlanePlane.jpg
Looking at it, as you PULL a japanese plane towards you, ignoring the vertical tail, if the wings don't provide a hand leverage advantage.....
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16th September 2020, 04:42 PM #28
Wonderful design Phil
You have in one fell swoop (Not a pun, but heavily weighted, aeronautical imagery embodied in the comment) enhanced your reputation exponentially with at least one judge. Damn! That has just upped the ante to at least three bottles of premium red!!!! And even then I have my doubts it will be enough. All you need now is one WA based judge to take up hang gliding so he can cross the border and I think you are home and hosed!
Regards
PaulBushmiller;
"Power tends to corrupt. Absolute power corrupts, absolutely!"
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16th September 2020, 05:16 PM #29
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17th September 2020, 08:04 PM #30SENIOR MEMBER
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The model plane plane has landed
Well look what landed on the workbench.
P9170781.jpg
This is a print done at a 45% of full size as that is about as large as i could fit on the small 3D printer
Below you can see the dovetails that will get hardwood infill to create hard wearing touch points for the sole.
I had some fun creating the one below as at 45% sizing that is 6mm tapering to 5mm wide and 3.5mm high. i chopped a 6mm wide section of a little bit hardwood floorboard, then decked it in the mill to about 5 high, hand sanded the bevels inserted into the slot then decked it to height back in the mill
P9170783.jpg
It's tempting to make a thicker version at the width and actually make a blade to fit as it would seem to be a great little size to do bevels.... i'd even leave the wings on as they provide some nice hand hold locations.
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