Author Topic: Chain saw blade carving jig (Read 7700 times)

Jason Wilkinson · « **on:** March 08, 2015, 01:37:47 PM »

HI all. Need to make a new set of blades, watched most videos of the carving that show the process which help in carving away the BULK of material, which is good
But, no one shows the process of MAKING THE JIG so how do you set it up ?
Jason

niall2 · « **Reply #1 on:** March 09, 2015, 04:33:42 PM »

hi Jason

i think Oz,s walkthrough link is still here

http://www.thebackshed.com/windmill/articles/ChainsawBlades.asp

i copied his jigs and its a fun way to make blades , this is the windward side jig base i set up

be carefull with the saw ...you'll have a few things going on in your mind at the one time

niall2 · « **Reply #2 on:** March 09, 2015, 06:57:57 PM »

mmm...cant edit that ...

the pic above is the windward side ....and i,ve lost all the pics of the downwind side ....

i should still have all the jigs somewhere though , i,ll see if i can find them

i used jigs for one 3.7m prop and blades for about five sets 2.4m props ....i,ll have a root

Jason Wilkinson · « **Reply #3 on:** March 10, 2015, 07:07:34 PM »

Still don't get it but thanks anyway for the link
Jason

niall2 · « **Reply #4 on:** March 11, 2015, 08:47:54 PM »

yea ....it is tricky just looking at pics ...dont give up just yet

Oz,s method is the simplest ...and best......it works because of its practicality.....

so ....to trim down the set up maybe think this way ....

take a piece of standard 5 foot plank lumber , say 9 by 2.5 inchs ....thats the base , place another 9 by 2,5 on top ( the blade blank ) , now screw two 5 foot guides to the base front and back ...say 4 inch by 1 lumber , these are the guides or rails the sawbar will run on , set them up even first , then drop the front one 3/8 of an inch lower , ( more than that for a practice run is good )

its just a practice......

clamp the root and lower blank well

thats the practice blade pitch cut ( a 3 degree pitch would actually work just fine all the way down ) ...cut down 80% of the blank ....its done

then reverse the blade....now you have to replicate the same angle all the way down on the back side ....just turn it over in the jig...........it will sit there

re adjust you guides , you want the same angle cut all the down but you also want to taper the thickness to leave the blade stronger at the root ...so the cut will taper out somewhat early ....

problem ...the sawbar teeth just cant rest and run on two pieces one inch wood guides , so sleds have to added underneath the bar where it rides , usually 2 rectangular pieces of 6 mm steel screwed to the sawbar ....now the teeth are clear

the saw will be riding to high now ( 6mm ) , so the wood guides can be lowered to accommodate for this

its sounds awkward , but once you take a cut and see the process the penny will drop

another way of using the saw is basically let it "eat" all the raw waste .....chainsaws get through wood like cutting butter

many more cuts than these could be used......

Jason Wilkinson · « **Reply #5 on:** March 12, 2015, 08:24:53 PM »

Ok it's a bit clearer now, but is that not a straight cut from tip to root on the trailing edge ? Hugh Piggott in his book don't show a straight cut (line) at the stations. Ie from tip to about station 3 a gradual slope then falls rapidly to the root. I will have to make the trailing support for the "saw blade" with a curve or bend as it gets to the root, thats my thinking.

niall2 · « **Reply #6 on:** March 12, 2015, 09:06:28 PM »

hi Jason

yes ....all Hughs blades have a gradual twist ...harder to replicate with the chainsaw method but it can be done ...

whether it is worth it with the chainsaw method ? ...maybe not ...ish...

the chainsaw method is the fast down and dirty version

i made two clones of Hughs 3.7m props just to compare ......one chainsaw with a compound twist ...one bog standard flat 3 degree all the way down...all basic dimensions were equal

both worked just fine and matched the alt well ...the curved prop did start up better ( and i,m sure is a stronger more efficient prop ) .....

3 degrees at the tip ....6 in the middle and whatever the root allows seems a good blade ...its everything else seems the worry ...ish

oztules · « **Reply #7 on:** March 13, 2015, 04:00:09 PM »

The moment you try the first test run.. it will become crystal clear.... until you actually do ( with any method) it is hard to get a three dimensional concept of the blade shape from the pictures and text ( Hugh or otherwise... you need to follow as best you can and then just do it.)... the moment you have something in your hand you will suddenly see why it looks right, or where you must have stuffed it up... correct and your now educated.... and it seems so easy....till then it is gobbledygook.

Chain saw blades are down and dirty, and reduce the blade time down to a 30 minute job to get 3 x 4meter blades stripped down, and only an hour or so to complete to painting stage for three blades... it is really fast have no doubt.

But it is not perfect, unless you use a lot of good jigging like I have seen from Niall... he makes beautiful blades that work well... I just make blades that work well, and look OK.

It will be terribly difficult to measure the difference between Hughs perfect recipie, and a fair approximation on the ole jig on the mill... both will perform fine.

.....oztules

Mary B · « **Reply #8 on:** March 13, 2015, 07:05:43 PM »

Maybe EMT conduit bent in the needed curve... use a block with a semi circle on the saw blade as a rider for the rail.

Jason Wilkinson · « **Reply #9 on:** March 13, 2015, 08:12:41 PM »

All my blades are curved (FBT full board thickness 12 ins from the root for 6 ft blades and they do work wonderful ) must one day try the straignt line twist chainsaw or not THanks again All
Jason

niall2 · « **Reply #10 on:** March 17, 2015, 03:25:29 PM »

glad it was of some help Jason .....i was trying to remember more about the process of making the jigs and found a few pics that explain better ....i,ll, tag these to the end of your thread if anyone else is interested

basically small templates were marked for each station on the blades , theses had the correct drop angles ( the optimal cut )
the jigs were adapted from these ...kind of ...join the dots , below pic is for the back side ....that was the bit i couldnt really remember...

station guides can be used for the windward side as well

some of actual cuts front and back ....

and the finished blanks...

[ Specified attachment is not available ]

niall2 · « **Reply #11 on:** March 17, 2015, 03:36:19 PM »

post timed out ...

the way the finished chainsaw blanks look....

Janne · « **Reply #12 on:** March 23, 2015, 05:12:59 AM »

Good stuff! I'm also tempted to try this method out soon. How much do you recommend leaving up to final planing and sanding with this method,, would 2-3mm be enough?

niall2 · « **Reply #13 on:** March 23, 2015, 04:33:51 PM »

hi Janne

2-3mm would be fine for a run with a planer or good electric sander ....but for the first cut i,d leave about 4mm to see how the saw behaves , the chain needs to be a little tighter than normal and very sharp . this will help give a "tighter" consistent cut to the marked lines....

i made an extra blank to practice on ....then moved on to the 3 blades , the practice blank will let you see how the saw behaves and cuts , if your happy with the cut but have a little too much left over you can drop the guides a little for the next blade .....

good clean knot free lumber makes things much easier as well ....cedar works fine too , i thought the saw would rip it a little
but it cut just fine , very soft

in the cut pic below the clearance above the line was about 4/5 mm ....it could have been closer

slow and steady , you can stop the cut at any time to check your clearances , i used to oil the bar/chain fairly regularly as well....

forgot to add as you cut along you can add a wedge to "open" the cut at the tip ....this is easier on the saw a little

MattM · « **Reply #14 on:** March 23, 2015, 10:35:21 PM »

Any reason a 110v chainsaw wouldn't work?

Smithson · « **Reply #15 on:** March 24, 2015, 08:22:25 AM »

Hi: Looks great. What do you use to get the trailing edge down to final thin edge? And to round off the leading edge? Thank you for sharing. Arch

niall2 · « **Reply #16 on:** March 25, 2015, 01:13:22 PM »

i,m not sure about using an electric saw Matt , i have one but mine would,nt have the power to deal with the root section of the blank
the petrol saw is a standard 50cc and for blades with a 8 inch chord ( or more ) at the root that power was needed

its good to have a little excess power .....

cutting down the blade (ripping) is a fairly dense cut , you dont get the usual clean wood chips......more like saw dust

for the trailing edge Arch i used a standard electric planer and then a good belt sander ( a spoke shave sometimes as well )

for the leading edge a good spoke shave will do a lot of the work ...it needs to be a good one though , not the bargain basement ones
( i have a few of those )

small knots as usual will slow down the finishing ...its worth getting clean lumber , my laminate blanks were fairy cheap and crude , just 4 pieces of planed off the shelf 4.5 by 1.5 (approx ) glued together for each blank....but this way mixing the grains was,nt a problem , if you were using more laminates then finishing with a planer and spoke shave gets more " unclean " ...( opposite grain )

solid pieces of wood are best but get more expensive and harder to get .............but are easier finished off

Mary B · « **Reply #17 on:** March 25, 2015, 06:11:38 PM »

My 14 inch electric saw handles 8 inch branches with ease... Only thing you might have to watch is motor overheat from to long of use at a time

niall2 · « **Reply #18 on:** March 25, 2015, 08:23:40 PM »

yes Mary B...electrics come in too many different flavors ...mine was from the cheap bargain section , still a nice saw

i did try to use it as a kind of "milling" machine for props ...the blank was on a kind of conveyor jig ....chop and move 8mm...ish

so the saw "eats" all the waste ...it did work well and ideal for indoor use

i never got it to work the way i wanted it to though , the backside of the small curved blade was problematic ( i was over thinking things ) and getting away from the kiss principle ........

i found a pic of the "flat" v "twist" blades , the flat is .....well ........very flat , but it certainly could perform at the top end though

all fun ...i guess you have to try what you have ...and take it from there

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Author Topic: Chain saw blade carving jig (Read 7700 times)