Post by: Shredd on August 16, 2019, 11:59:01 AM
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Post by: Mad Max on August 16, 2019, 03:16:52 PM
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Post by: Shredd on August 19, 2019, 02:21:49 PM
Post by: Crooked Stic on August 19, 2019, 04:34:39 PM
Post by: Shredd on August 19, 2019, 04:45:17 PM
Post by: Mad Max on August 19, 2019, 04:59:55 PM
:campfire:
Post by: Shredd on August 19, 2019, 05:01:26 PM
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Post by: Flem on August 19, 2019, 08:32:42 PM
Post by: Mad Max on August 19, 2019, 09:05:27 PM
Post by: Shredd on August 19, 2019, 09:29:52 PM
Flem... The plan is to make this bow for people who draw under 27"...
I did a quick shoot before dark... It shoots nice and seems to be pretty quick... I need to make a skinny string for it before I can put it through the chrony...
Post by: Crooked Stic on August 19, 2019, 09:49:04 PM
Post by: Shredd on August 19, 2019, 11:40:07 PM
I went with my standard hyper lam... I think it is a bit too thick in the tip area creating the instability... When you scale down I guess you have to scale everything down... I will try and thin that out a little and pull in the the wedge section at the fades about 3/4" or thin it out a hair... On these limbs I might try trapping the last 8" of them and see what happens...
I was just looking at the pic where the bow is drawn... Being that the limbs are over 1" above where they would be on a one piece bow and that riser is extra deep, the bow in the pic is drawn to about 27 1/2"... I will measure it tomorrow...
Post by: Shredd on August 20, 2019, 04:17:46 PM
Post by: Hoosierarcher88 on August 21, 2019, 03:20:18 AM
Post by: Pat B on August 21, 2019, 08:24:38 AM
Post by: TradBowyer on August 21, 2019, 12:28:39 PM
Post by: Shredd on August 21, 2019, 02:10:41 PM
I have a lot of work cut out for me but man am I gonna learn so much from this... Here are some pics at 5*, 7* and 9* pad angles... They are all drawn to about 27" in reference to the limbs and not the riser... I went from 32# on the 5* riser to 28# when I put the limbs on the 9* riser...
Post by: Shredd on August 21, 2019, 02:18:25 PM
:shaka: I will try to comment or or discuss all of your advice and comments so please keep them coming... :shaka:
Post by: Mad Max on August 21, 2019, 03:32:30 PM
What is the angle on you normal bows?
:thumbsup:
Post by: Shredd on August 21, 2019, 08:39:47 PM
Well I shot it through the chrony as is with a 6 1/8" brace height, weight at 28" is 33.3#, 334gr. arrow drawn to 28" - 184fps...
Shot a 305gr. arrow at 189fps...
As a one piece and at 6 3/4" brace height I am guessing she will be shooting in the mid to high 170's... I could be wrong... All this translating from a 3 piece to a one piece is beginning to confuse me...
Post by: Mad Max on August 22, 2019, 09:37:22 AM
I would make my 1P riser as long as the TD riser + 2" or so each side
same angle for the fades as the butt wedges are.
Post by: Crooked Stic on August 22, 2019, 10:44:51 AM
Post by: Shredd on August 24, 2019, 03:42:42 PM
I did some math and I think I am pretty close to what the speeds would be as a one piece bow... The speeds may be pretty close no matter what angle riser I use... Probably because of the very thin limbs... With the change of each 2* angle the draw weight changes 2#... So to do a true test you would need 3 sets of limbs measuring all the same draw weight at different angles... Here are some speeds all at 5* and 7* at 6 3/4" brace and 9* at 6 7/8" brace... (was a little short on the string to get 6 3/4")
5* riser 32# string tension 52.4# / 81.8%
26" 27" 28"
303gr. 166 174 182fps
334 160 169 177
410 147 154 162
7* riser 30# string tension 51.5# / 85.8%
26" 27" 28"
303 162 170 178
334 157 165 172
410 144 150 157
9* riser 27.9# string tension 50# / 89.6%
26" 27" 28"
303 156 165 172
334 151 159 167
410 138 145 153
As you can see the string tension is greatest with the 9* riser and it also had the best numbers on the DFC charts... When I am comparing two bows of one set design the bow with the better DFC and higher string tension usually results in better performance... Being that I am dealing with three different angles (designs) who knows what will give the optimum performance... DFC's and string tension may not be comparable from one design to the next in this case...
Post by: OkKeith on August 27, 2019, 02:08:46 PM
Very cool data you are collecting! I have a quick question about your construction methodology (unless it is Super Secret Squirrel Stuff).
Are you using a jig on your table saw to run the angles on those risers? I figure I have a year or so to build a few bows so that I can up my build game before next years bow swap. I like the idea of making a take down but don't see myself adding any major power tools to my cramped home shop. I have a bandsaw at my folks place as well.
My thought was to make a tablesaw sled with hold downs for the risers. Since I am thinking about a D/R longbow I am considering a 6-6.5 degree angle on the risers.
Also, do you have two forms and run both limbs at the same time or one form and run one limb and then the other?
Thanks for the help!
OkKeith
Post by: Mad Max on August 27, 2019, 02:16:37 PM
If you table saw blade is not perfectly square your limbs will be twisted.
Post by: OkKeith on August 27, 2019, 05:04:12 PM
I figure EVERYTHING will have to be as square as possible! The blade to the tabletop, the sled to the blade and the material will have to be dead square. I will do my best but I doubt it will be anywhere near perfect.
What is your suggestion on how to cut the angles on the riser?
OkKeith
Post by: Mad Max on August 27, 2019, 05:58:53 PM
hold the test piece up so you can see light between the square and wood.
Keep moving your blade a little until you get it where you want it.
Google Machinist Square
Good luck
Post by: Shredd on September 05, 2019, 03:49:42 PM
I use a bandsaw and free handed these since they were one-offs... I would make a jig if I was making a certain riser all the time... But yes, you can use a table saw and a jig and pretty much do what Max said... You can touch it up on a disc sander set accurately at 90* if you have one...
I only have one form as for now, these are experimental limbs... One form should be fine for most people unless you were gonna go into business and mass produce them... I which case you might want to have 10 forms... :cheesy:
Being that you are going to make a 3pc... I would do as I am... Make a couple of risers with cheap or defected wood and test your limbs at different angles to get the best performance, stability and shootability out of them... You can always shim the limbs a degree or two to finely tweak it to what you want... I would do this method before you spend time and money on a pretty riser that makes for a sub-par bow...
Post by: Crooked Stic on September 05, 2019, 04:05:12 PM
Post by: OkKeith on September 05, 2019, 07:37:24 PM
When you say "profile jig"... are you doing this process on a milling machine?
Thanks,
OkKeith