What I've been up to

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dawallace45
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What I've been up to

#1 Post by dawallace45 » Tue Oct 26, 2010 9:39 am

Well over the last few weeks I've been busy , I started off building a 54 # bow that turned out at 64# , think that was more to do with the number of laminations of Tulip wood I was using , but the up side of it was a mate turned up a few days later had a look and said great I'll have that and bought it on the spot ,

16" riser , Laminated Kwila and one lamination of Sallie wattle and three of Tulip wood

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and the bow is fast ,

Any way with that one out of the way I set about building another 50# bow , this one come out at 46# , damn I used to be better at this , most of the bows I've built come out with in two # of my target weight , I think this may have been because most of them have been made using Vertical flooring bamboo which is very consistent , the Tulip wood and Sallie wattle are more interesting and mostly faster but it seems harder to be right on the money with target weight , any way the bow come out nice

16" riser , Laminated Tulip wood and Sallie wattle , 4 laminations of Tulip wood , very slight hand shock but I'm going to experiment with bracing height to see if it makes a difference

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I run out of Fibreglass laminations late last week so to keep boredom from setting in I decided to try making a laminated bow with out glass , decided on a 14" riser like my old Howard Hill bow , three laminations of Tulipwood , two on the back and one on the belly and a lamination of Sallie wattle , with the thicknesses used if it were a glass bow it would have come out 65 to 70# but it come out at 41# and takes on a lot of string follow

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I haven't finished it off yet and probably won't for a while , it doesn't seem to shoot too bad at all and has potential , the tiller is nice straight off and I was thinking of maybe backing it with Bamboo if I ever get a chance to get down to Bamboo Oz to pick some up , it would be a shame to waste the work in it so finishing off the tips , final sanding and applying finish will wait .

On the subject of finish I've come to the conclusion that I can't apply finish to save my life , I can make a bow , I can even make a pretty bow , hell I can even make a fast bow but putting a spray gun in my hand is a crime against nature ,

If I knew any one close who was good with a spray gun I'd pay them to do my bows but I don't , I have three spray guns , two of them are HVLP , one of those is a touch up gun , I've tried the spray cans , Septone , PowerPlus and a few others , with the guns I've been using PPG Premium Clearcoat and lately K&H Top Clearcoat , the K&H seems a harder finish than the PPG but takes longer to attain full hardness , several days in fact , I've had it leave marks on a bow if I put it on a bow rack 48 hours after spraying ,

Now I am learning and getting a little better [ but not much better ] but I have temporarily suspended my fight with the the spray gun and the latest bow has had 4 coats of Minwax Wipe on poly , I think it needs another two coats , if any one has used this product on bows can they tell me the process for best results , Please !!!

David

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Re: What I've been up to

#2 Post by Stickbow Hunter » Tue Oct 26, 2010 12:16 pm

this one come out at 46# , damn I used to be better at this ,
Welcome to bow making mate. :lol:

Good work mate, you have been busy.

I like to spray my bows and I think you will get the hang of it eventually; make sure you haven't got too much paint coming out of the gun and apply thinner rather than thicker. I have no experience with the Minwax.

Jeff

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Re: What I've been up to

#3 Post by Bill » Tue Oct 26, 2010 12:59 pm

:) Well done, nice looking bows you've put together there, David.

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Re: What I've been up to

#4 Post by dawallace45 » Tue Oct 26, 2010 1:02 pm

Jeff

Thanks ,

Yeah I know the more you experiment with different timbers the more chance there is of being off your target weight and to make matters worse I lost the build notes from almost 20 bows when a wind storm went through my workshop

One thing I have found interesting is that even for the same thicknesses of laminations the weight will change by having a thicker belly lam , I really don't understand this and it's only from the evidence of 4 bows made with exactly the same timber but different lamination thicknesses on the belly lam , so it's not gospel

While I'm not as bad as I once was at spraying I dispare of ever getting the level of finish I want to achieve , don't want a high gloss finish just a nice even satin finish

Suppose I could buy a book on spray finishing , looked in the Gladstone library but there was none available

David

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Re: What I've been up to

#5 Post by dawallace45 » Tue Oct 26, 2010 1:06 pm

Bill

Thanks , past 25 bows so far and each is a little better , stopped counting at 25

David

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Re: What I've been up to

#6 Post by Nephew » Wed Oct 27, 2010 12:20 pm

I'm constantly being amazed at he quality of the bows made in peoples sheds, etc here at Ozbow. Well done, Mr. Wallace. :D
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Re: What I've been up to

#7 Post by longbow steve » Wed Oct 27, 2010 12:46 pm

dawallace45 wrote:Jeff

Thanks ,

Yeah I know the more you experiment with different timbers the more chance there is of being off your target weight and to make matters worse I lost the build notes from almost 20 bows when a wind storm went through my workshop

One thing I have found interesting is that even for the same thicknesses of laminations the weight will change by having a thicker belly lam , I really don't understand this and it's only from the evidence of 4 bows made with exactly the same timber but different lamination thicknesses on the belly lam , so it's not gospel

While I'm not as bad as I once was at spraying I dispare of ever getting the level of finish I want to achieve , don't want a high gloss finish just a nice even satin finish

Suppose I could buy a book on spray finishing , looked in the Gladstone library but there was none available

David
Hi Dave, The bows look good as usual.
I would say a variation in taper may be the culprit in the weight change?Rather than the size of the belly lam? Measuring the stack at one point leaves you open to these changes if taper changes.
Steve

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Re: What I've been up to

#8 Post by dawallace45 » Wed Oct 27, 2010 12:49 pm

Thanks Morton

David

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Re: What I've been up to

#9 Post by dawallace45 » Wed Oct 27, 2010 12:57 pm

Steve

Thanks

I use one taper on the belly , .002" per inch , the rest of my laminations are parallels so while the thickness of the taper may change the rate of taper doesn't

David

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Re: What I've been up to

#10 Post by longbow steve » Wed Oct 27, 2010 1:16 pm

Yes but % taper may alter. .002" taper on a 30# bow is a greater percentage taper than .002" on a 60# bow.
Measure at the fades and below the tips and compare.
I could be wrong but the times I have missed weight was when I wasn't adjusting taper with draw weight adjustments. Steve

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Re: What I've been up to

#11 Post by dawallace45 » Wed Oct 27, 2010 1:48 pm

Steve

The 4 bows I based that statement on were all set out at the same time , the timber was the same and the over all thicknesses the same , the only difference was the thickness of the tapers that went on the belly , thickness of lamination bundle at tips and thickest part all the same , I had set them out as I planed to make 4 bow all the same weight one after the other

David

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Re: What I've been up to

#12 Post by longbow steve » Wed Oct 27, 2010 2:07 pm

mmmm? I will have more of a think. Maybe Jeff may have struck that? Steve

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Re: What I've been up to

#13 Post by longbow steve » Wed Oct 27, 2010 2:20 pm

Thought about it more :D , because you are altering the belly lam thickness but remaining with the same overall core thickness you are reducing the taper because the belly cores are shifted out towards the tips to allow for the handle. If you measure the bows at the same point towards the tip you might find the thickness variation to account for the change.
Works in my mind I think :D .

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Re: What I've been up to

#14 Post by Stickbow Hunter » Wed Oct 27, 2010 4:08 pm

I keep the belly lam on all my bows the same - thicknes and taper wise. I can't see that causing your bow weight difference though.
longbow steve wrote:Thought about it more , because you are altering the belly lam thickness but remaining with the same overall core thickness you are reducing the taper because the belly cores are shifted out towards the tips to allow for the handle. If you measure the bows at the same point towards the tip you might find the thickness variation to account for the change.
Works in my mind I think .
I don't think that would be it either Steve because if Dave made his belly lam thicker he must have made his parrallel lams thinner in order to keep his overall core thickness the same.

The problem may lie in the glass. Glass stiffness varies with coloured glass producing a heavier poundage bow than clear glass. Even strips of the same colour can vary in stiffness and I believe this is what can cause the weight variances when you are using lams made from the same block of wood (the wood of course can and does vary in stiffness also). I don't know of any bow maker who has not experienced bows going wrong weights. I remember Mark Kimber complaining once that he made to identical bows yet one came out seven pound lighter than the other; I just gave a knowing smile. :lol: I really think I should spine test the glass to check the stiffness.

Another thing Dave; did you check the glass thickness as it can vary quite a bit (a few thou). If you use two pieces that are thicker or thinner than what you thought it was the draw weight can either be over or under your taget weight by quite a bit.

I always say that getting the draw weight spot on is one of the hardest things about bow making. :D

Jeff

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Re: What I've been up to

#15 Post by greybeard » Wed Oct 27, 2010 7:29 pm

I may be wandering a little off the topic but the following email to Bingham's was prompted by a post from Kimall regarding clear Bo-tuff. I experienced a similar situation where clear glass appeared to yield lower poundage.

From: Greybeard [mailto:greybeard@pcsol.com.au]
Sent: Wednesday, September 15, 2010 5:44 AM
To: 'Bingham Projects Inc.'
Subject: Bo-Tuff clear glass.

Hi Elmont,

I have a question regarding Bo-Tuff clear glass.

For the given thickness of the laminated core of a bow does clear glass i.e. .043 ULS yield a lower performance/draw weight than coloured glass of .040 ULS?

I am led to believe there is less glass fibre in clear glass. If there is a notable difference is there a percentage value that I should build into the core of a bow?

Regards,

Daryl.

Hi Daryl,

Thanks for your e-mail. Thickness for thickness, they are the same. The same limb thickness with black will yield the same weight as the same limb thickness with clear. The black glass is harder, not stiffer.


Sincerely,
Elmont

Upon checking the thickness of some clear glass I had in stock some was 10% under thickness. As my digital vernier calipers have not been certified as 'accurate' I can not dispute the variation in thickness as stated.

A problem that I encounted when using hard rock maple for core material was that for a given core thickness with each new supply I purchased I could be plus or minus 5# of the targeted draw weight.

I think my switch to vertical bamboo is yielding more consistent results.


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Re: What I've been up to

#16 Post by Stickbow Hunter » Wed Oct 27, 2010 8:27 pm

Interesting Daryl but that isn't quite what myself and some others have found. The clear glass is most definately softer, especially in more recent years. The clear glass now days is nowhere near the quality of the stuff we used to get back in the late 1980's early 1990's which actually was clear. :D This later stuff has all the streaks etc in it and doesn't look the best with darker woods as it shows up the streaks more. Over the years the coloured glass has tended to produce bows with two or three more pounds draw weight than with bows using the same core thickness but clear glass.

I mic all my glass and like you find its thickness does vary quite a bit. It can often vary .002" over its length. It also can be a few thou over or under what it is supposed to be. I will often end for end glass to match it up and if it is too thick I will regrind it but I hate grinding glass. :lol:

Jeff

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Re: What I've been up to

#17 Post by dawallace45 » Thu Oct 28, 2010 6:52 am

Jeff

Hadn't thought about the glass , did measure the glass for the last bow I built and there was .003" difference between the two pieces , in your opinion what difference could that make to finished bow weight ?

David

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Re: What I've been up to

#18 Post by Stickbow Hunter » Thu Oct 28, 2010 9:16 am

Dave,

You don't say if your one strip was the proper thickness but let's say it was and the other was .003" under; this could (depending on your bow design - amount of reflex etc) drop your draw weight by 2# - 3#. If both strips were .003" under what they should have been then you could easily throw 5# - 6# under weight.

Jeff

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Re: What I've been up to

#19 Post by dawallace45 » Thu Oct 28, 2010 9:33 am

Jeff

I use Black glass and I figure that with .050" glass a difference of .002" + or - would be pretty normal but for those particular laminations one was .052" and the other .055" ,

Didn't think to check thickness on the glass from the 4 bows in question , but they did vary by 9# from the lightest to heaviest , other than the glass the only difference was the Belly taper and the thicker it was the heavier the draw weight [ thickness of the tapers varied by .020" ] , but as you say that could at least partly be explained by differences in glass

David

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Re: What I've been up to

#20 Post by longbow steve » Thu Oct 28, 2010 10:16 am

Hi Dave, I still believe it is due to shifting the thick butt end of the lam out board toward the tip effectivley increasing your stack :) .
If you kept your taper on the back of the bow and adjusted a paralell on the belly you would not have the issue.

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Re: What I've been up to

#21 Post by Stickbow Hunter » Thu Oct 28, 2010 11:24 am

longbow steve wrote:Hi Dave, I still believe it is due to shifting the thick butt end of the lam out board toward the tip effectivley increasing your stack :) .
If you kept your taper on the back of the bow and adjusted a paralell on the belly you would not have the issue.
Steve,

Can you explain this further as I can't grasp what you are saying (not unusual for me :lol: ) no matter how I look at it.

You see the butt end on the belly is always going to be in the same place regadless of how thick it is. What Dave had done - at least from what I understood he was saying - is he thickened the belly lams on some bows but also had to thin the parallel lams on the back to maintain the same core thickness. Doing it this way the stack thickness remains the same anywhere along the limb on all of the bows doesn't it? :? I may be missing something here and that is why I ask.

Thanks

Jeff

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Re: What I've been up to

#22 Post by longbow steve » Thu Oct 28, 2010 12:04 pm

If you measure your stack at the centre of the lamination lengths that will be a constant figure. If then you shift the tapers out 3-4 inches to allow for the handle you are shifting the thickest part of the lam further out meaning your tips will be thicker aswell.
It wont be much increase in thickness but .2mm-.5mm over a whole limb will increase weight and will be compounded the more Dave adjusts the thickness of the belly taper.
Steve

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Re: What I've been up to

#23 Post by Stickbow Hunter » Thu Oct 28, 2010 2:50 pm

Thanks for the reply Steve and understand what you are saying but I still don't see that there would be any change in thickness of the stack between Dave's four bows - see below for the explanation.
longbow steve wrote:If then you shift the tapers out 3-4 inches to allow for the handle you are shifting the thickest part of the lam further out meaning your tips will be thicker aswell.
Yes that is correct but Dave has done eaxatly that on all the bows as most of us do. He is saying (from my reading of it) that the only difference in the bows is he has made the belly lam thicker on some but has kept his core thickness the same by making the parallel lams thinner. What this does is keep the thicknes of the cores on all four bows exactly the same - same thicknes at the middle, tip or wherever you wish to measure them. By adding to the one (increasing belly lam thickness) and taking from the other (decreasing the parallel lams an equal amount) will result in the stack of all four bows remaining the same. If I am wrong with this assumption Dave & Steve please let me know.
It wont be much increase in thickness but .2mm-.5mm over a whole limb will increase weight and will be compounded the more Dave adjusts the thickness of the belly taper.
I don't believe that is right Steve because as Dave increased his belly lam thickness he reduced the core thickness by making the parallel lams thinner so that his overall core thickness remained exactly the same on all four bows; not thicker as you are saying above. The belly lam alone increases in thickness at the tip as he increases its thicknes but the rest of the core is reduced in thickness by the same amout so the overall thickness of the core measured at the tips (or anywhere else) does not increase but remains exactly the same.

I hope that explains my thinking better. :D

Jeff

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Re: What I've been up to

#24 Post by dawallace45 » Thu Oct 28, 2010 4:19 pm

Jeff

Yes , your reading of it is correct

Steve

Thickness at mid point on the lam stacks was all the same or at least with in .002" all up, after glue up this had changed to .003 " all up variation , possibly because of some very slight difference in the amount of epoxy , my thoughts were that a .003" difference was only about 1# any way , ,

My equipment just isn't capable of grinding with any more accuracy than this any way and while the manufactures claimed that my digital verniers were accurate to with in .0005 " + or - and it does seem to be reasonably accurate when compared against my micrometer but I'd say that it was probably more like .001" + or - but I'm taking the measurements at face value

The only way my putting the taper on the belly would make a major difference in stack thickness is if the taper was slipping up or down the riser on gluing up but the chance of this happening is remote as I generally put a thin spacer block the right length on top of the riser to stop this movement , also on my trial run where I put every thing in the press with out epoxy I mark the ends of the laminations and cut them so they all come to the same length when glued up , helps me make sure the tapered lams and glass laminations haven't slipped down when I glue up

The only other way I can see it making a major difference is if some of the bows had a 16" riser and some a 18" riser but since all the bows had a 16" riser every thing was constant ,

Yes I do do it the simple way and take my measurements to calculate weight from the thickest point of the stack and when I glue up the bow the belly laminations will have been moved out to accommodate the handle there by making the limb tips thicker than they originally were but that shouldn't make a difference as it's not the tip measurements I go by when calculating bow weight , the only reason I did check that time was that I was intending all 4 bows to be the same and some time I can be a little obsessive with measurements , [ mind you my wife reckons that any one who tiles there workshop floor is a lot obsessive ]

David

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Re: What I've been up to

#25 Post by longbow steve » Thu Oct 28, 2010 4:37 pm

Yeah I think my reckoning is flawed sorry :) . However like Jeff I keep my belly lams a constant (mainly to make it easier to form to the riser shape) and adjust my stack with the other core lams.
Steve

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Re: What I've been up to

#26 Post by Stickbow Hunter » Thu Oct 28, 2010 4:52 pm

The main thing is that we got to understand the process Dave used. The good thing is with us discussing this subject some of the other fellas may learn from it and that is one of the main aims of the forums.
longbow steve wrote:(mainly to make it easier to form to the riser shape)
Main reason I do it to mate.

Jeff

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Re: What I've been up to

#27 Post by dawallace45 » Fri Oct 29, 2010 7:02 am

However like Jeff I keep my belly lams a constant (mainly to make it easier to form to the riser shape) and adjust my stack with the other core lams.
Have been thinking of the same thing recently to as you say
make it easier to form to the riser shape
and from the bows I've done that were all parallel and no tapers it is a lot easier to get a parallel belly lam to form along the riser but have held off as I prefer to use a full length laminations on the main lamination stack and don't want to stuff around using two tapers and having to worry about a clean join in the middle ,

Every thing I do is set up to make the gluing up process as quick painless and accurate as possible

Have been thinking of gluing up a couple of tapers to a full length parallel lamination to make a master but haven't gotten around to it and have been a little worried about getting a clean even glue line with no variations to throw it out

David

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Re: What I've been up to

#28 Post by longbow steve » Fri Oct 29, 2010 7:45 am

Hi Dave, I make my full length tapered lams using a half length master taper. Easy :)

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Re: What I've been up to

#29 Post by Gringa Bows » Fri Oct 29, 2010 7:55 am

i do mine the same as Steve,and it's no drama's after youve done a few.

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Re: What I've been up to

#30 Post by greybeard » Fri Oct 29, 2010 8:08 am

I've started to do mine the same way and as Rod said "it's no drama's after youve done a few."

Practice on some scrap timber.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
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