Crossbows - Everything about Building, Modding, and Using your Crossbow Gear

Latest topics

» Beware of Alchem
by Archer46176 Today at 3:33 pm

» How to measure and cut leather for prod
by Celtic Archer Yesterday at 5:56 pm

» Crossbow with built in lever?
by John Edgerton Thu Aug 17, 2017 12:38 pm

» Of Bows and Torsion Engines
by JacobL Mon Aug 14, 2017 12:03 pm

» Early Lever and pin Crossbow
by topfmine Mon Aug 14, 2017 8:56 am

» Crusader crossbow
by topfmine Mon Aug 14, 2017 8:53 am

» First Efforts
by rickraedeke Tue Aug 08, 2017 5:25 am

» aluminum prod
by Phil Abrahams Fri Aug 04, 2017 8:38 am

» First whitetail buck taken with medieval crossbow
by Phil Abrahams Fri Aug 04, 2017 3:38 am

» Airsoft Crossbow
by JacobL Wed Aug 02, 2017 9:11 pm

» Questions about steel prod specs
by JacobL Mon Jul 31, 2017 8:25 pm

» Faking a medieval composite crossbow prod.
by JacobL Mon Jul 31, 2017 8:13 pm

» Airsoft Bow
by JacobL Sun Jul 30, 2017 1:56 pm

» Hello All!
by JacobL Sun Jul 30, 2017 12:54 pm

» Padre Island Bow
by Geezer Wed Jul 26, 2017 12:14 pm

» Blocked pictures by Photobucket
by Crossbowmen Mon Jul 24, 2017 1:33 pm

» Geezer website?
by Geezer Fri Jul 21, 2017 3:01 pm

» Could I get advise on order of operations?
by Bs1110101 Wed Jul 19, 2017 4:02 am

» Renaissance Sporting crossbow
by chaz Mon Jul 10, 2017 12:22 am

» Welcome! Welcome! Welcome!
by Agniznag Sat Jul 08, 2017 12:26 pm

» The Arbalist Guild - Around the World
by Agniznag Sat Jul 08, 2017 11:56 am

» opinions please
by Geezer Thu Jul 06, 2017 10:19 pm

» Hello all!
by Tarzan65 Thu Jul 06, 2017 10:54 am

» Yet another one
by Daniel Levesque Sun Jul 02, 2017 9:37 am

» Renaissance peep sight
by kenh Fri Jun 30, 2017 4:48 am


    Riser Material

    Share
    avatar
    William Tell
    Fresh Blood

    Doesn't mean
    I'm new to crossbows


    Fresh Blood Doesn't meanI'm new to crossbows

    Posts : 44
    Join date : 2010-01-08
    Age : 59
    Location : Malte Europe

    Riser Material

    Post by William Tell on Wed Apr 28, 2010 7:32 am

    Hello Guys !

    At last I received the Excalibur Limbs. However I went out to this steel & iron vendor the other day and inquired on what a piece of Aluminum approx : 20cm x 15 x 6 cm would cost, in order to mill out the riser.
    Well owing to the limitations of shops that sell aluminum in Malta, there ain't much where one can inquire. However the price for this piece of aluminum was around $70. I think you all agree that this is somewhat absurd. So I had to decide on an alternate material from which I can make a good riser.

    Any suggestions guys !! Oak? American walnut? would appreciate your feedback Evo, Geezer, Pavise.

    Thanks guys

    William
    avatar
    Pavise
    Dear Friend, You will be Greatly Missed.
    Dear Friend, You will be Greatly Missed.

    Posts : 128
    Join date : 2010-02-07

    Re: Riser Material

    Post by Pavise on Wed Apr 28, 2010 11:09 am

    Hi William Tell,

    Seems like everybody has left the building.


    The problems in making a serviceable riser without access to conventional materials and or machinery are ones that I have pondered quite often. A one-piece prod is much simpler to work with but a two-piece prod presents a whole lot more in the way of engineering. This is because the two separate limbs are forever trying to separate at the middle where there is no connective tension other than that provided by the fasteners attached to the riser. This tendency to separate can be mitigated by a suitable strap of metal that attaches to both limb bolts; thus effectively joining both limbs together. But it’s not that easy and the riser has to be strong enough to resist bending in two planes; one more than the other. The main load comes from the limbs being bent back towards the latch and the other is when the limbs retract to their rest position with some violence before coming to a complete stop. A riser must also be capable of containing threaded fasteners unless common nuts and bolts are used instead. Special threaded inserts can be employed whereby bolts can be fastened through the limbs and into these. But whatever method we choose we must also use a means of spreading the load under the heads of these bolts otherwise they will quickly wear, if not tear, through the limbs. Hex socket cap screws in the order of 8 mm or 5/16” are the usual sizes, with a thick countersunk washer under the head to spread the load. The hole through the limb must be very slightly oversize to that of the bolt too.



    Machined risers that we see on production crossbows are typically made from 6061 or 7075 aluminum alloy. Sophisticated computer numerically controlled (CNC) milling machines make this task a whole lot easier, but the initial investments can be enormous! A home machinist can often replicate this method on manual type mills but again he or she must have access to the base material. And engineers have designed these various metal risers to bring the limbs up as high as possible in order to minimise parasitic string drag along the deck and it is this feature that largely dictates their choice of riser material.



    Undoubtedly there are woods that are strong enough but in order to leave sufficient bending resistance they can be invariably bulky when shaped for a crossbow riser and not always pleasing to the eye. Laminating several types of hardwood together (in a horizontal plane) can increase the strength considerably and a riser block made this way might easily be machined or shaped with common tools. One feature we see on a lot of commercial risers is the groove or channel that serves to stop the limb from rotating about a single limb bolt. Two bolts can accomplish the same thing but also weakens the limb in this critical area. Other methods uses one bolt and a short dowel pin in the riser that only enters the limb a shallow amount. But a flat faced riser can be more easily made and a separate channel metal piece then fastened to this which will serve to contain the limb end just as well. In fact if this sheet metal, or even plastic, (heat bendable thermoplastic) channel is made long enough it will also serve to bridge the two limbs together. A better idea would be to incorporate a metal stirrup in this arrangement too.



    Another riser material that might be used is fibreglass reinforced resin or a large block of micarta. An article on The British Blades website describes how to make a type of micarta by press moulding many layers of denim material soaked in epoxy resin which when cured can be shaped into attractive and serviceable knife handles etc. I’ve often thought about making a very fancy looking riser and latch cover using this method.

    [url=http://www.britishblades.com/forums/showthread.php?21836-Home-grown-quot-micarta-quot-(picture-intensive]



    And I’m pleased to know that the Excalibur limbs finally arrived okay. For a while I thought that you had given up. It’s good to learn that your project is still ongoing.



    Bonne chance mon ami,



    Pavise
    avatar
    Ivo
    Admin
    Admin

    Posts : 1041
    Join date : 2009-11-25
    Age : 29
    Location : NJ, USA

    Re: Riser Material

    Post by Ivo on Wed Apr 28, 2010 5:09 pm

    Seems like everybody has left the building.

    I got really sick and have this terrible cough that got my family so worried they put me to bed, took away the computer and barricaded me with medication ...as for others, perhaps it is good that they are taking a little break...who knows may be they're cooking up something interesting!

    So ok...Riser Material...

    Pavise,

    Good stuff!

    With fiberglass being one of the choices I can even link to a good example of how to make such a riser >>>Link



    ...and well maybe not the lightest of materials, but still a good choice is "Steel"...if we pop onto E-bay there is now a crossbow being sold with just such a riser.




    As I've sorted it out for myself - it all comes down to how you design the riser.




    * *
    ~ "I don't have any special talents. I'm only passionately curious."
    * * *
    ~ "All Genius is Simple"
    * *
    avatar
    Ivo
    Admin
    Admin

    Posts : 1041
    Join date : 2009-11-25
    Age : 29
    Location : NJ, USA

    Re: Riser Material

    Post by Ivo on Wed Apr 28, 2010 5:49 pm

    As for the structural aluminum, I hear A LOT about "forged aluminum" and that it's some really nice stuff. Can anyone tell us a little bit about it and how is it different from the milled or cast parts in crossbow making?




    * *
    ~ "I don't have any special talents. I'm only passionately curious."
    * * *
    ~ "All Genius is Simple"
    * *
    avatar
    Pavise
    Dear Friend, You will be Greatly Missed.
    Dear Friend, You will be Greatly Missed.

    Posts : 128
    Join date : 2010-02-07

    Re: Riser Material

    Post by Pavise on Wed Apr 28, 2010 7:42 pm

    Hi Ivo,

    Sorry to learn that you've been unwell and I hope you're feeling better now.

    Given enough pressure, some metals, as we know, can be made into incredibly detailed shapes. However we must not equate "forged aluminum" risers with what blacksmiths do with fire and anvil. Whilst some grades of aluminum will lend themselves to a little shaping while hot, or even when cold, this is not the easy way to make such a crossbow riser. A forged aluminum riser would have to be made with a very large sophisticated press that produces perhaps hundreds of tons to literally queeze a billet of aluminum into a tool steel die that again is very expensive to make. High performance engine pistons as well as connecting rods are typically made this way. Such industrial forging often involves combined induction heating under precisely controlled conditions and again is prohibitively expensive unless many parts are to be made and the investment costs ammortised over thousands if not millions of such parts. But I have seen farriers (horse shoeing blacksmiths) forge shoes from aluminum during competitions which are designed to test their ability to work with unusual materials. Yes, race horses use aluminum shoes because they are light weight, but these are mass manufactured rather than made one at a time at the forge, for obvious reasons. When worked, such as being shaped with hammers etc., non ferous metals such as aluminum "work harden" and have to be frequently anealed before work can continue. The softer alloys such as 3003 aluminum can be heated until the smoky film from an acetylene flame burns off as an indicator of enough heat to make it bend easier or soap rubbed on and the metal heated until the soap film turns black is another way.

    Your second picture shows the use of an existing metal profile such as "angle" which makes it convenient for our uses. But the bolts shown are in more tension and bear the full load of the stressed limbs. No big deal if reasonable loads are spread over a large enough area by the use of suitable flat washers. My old Black Widow take-down recurve is made this way. And the Russian fiberglass riser example link needs no translation to be understood.

    Enough from me tonight.

    Pavise
    avatar
    Ivo
    Admin
    Admin

    Posts : 1041
    Join date : 2009-11-25
    Age : 29
    Location : NJ, USA

    Re: Riser Material

    Post by Ivo on Sun May 02, 2010 12:22 am

    Pretty cool stuff...never knew about the aluminum horseshoes ...really awesome stuff! I asked about forged aluminum
    because I talked with a guy once on another forum where we were discussing aluminum castings with pores in them and if it was possible to forge these castings to final shape in order to try and lessen the negative effect of the porosity....so I went ahead and tried > of course knowing absolutely nothing about what you just explained and therefore ended up hammering the casting into aluminum "slush" ...Guess I just overheated them then, but I'm glad to learn that it is indeed possible to forge aluminum to some extent.

    The Idea of using easily obtainable parts like metal plates and other various protrusions like that angle should make it possible to put together a riser rather cost effectively. For example the riser on Twinbow built by SCM looks to be composed of metal plates of varying thicknesses.



    The Twinbow itself is pretty much made from plates and tubes which in all is a pretty cool concept.




    * *
    ~ "I don't have any special talents. I'm only passionately curious."
    * * *
    ~ "All Genius is Simple"
    * *
    avatar
    Geezer
    Master Crossbowyer
    Master Crossbowyer

    Posts : 945
    Join date : 2010-01-12
    Age : 69
    Location : Austin, Texas, USA

    Aluminum slush

    Post by Geezer on Sun May 02, 2010 8:36 am

    From my limited experience, I can tell you that aluminum work-hardens very easily. A little hammering and shaping is OK, but hammer just a bit more and everything starts to crack. Add a few strokes and your work-piece crumbles. Re-heating and annealing every few strokes will allow you to hammer some more, IF you do it before things start to crack. Not a friendly metal for smithing. Geezer
    avatar
    tod
    Fresh Blood

    Doesn't mean
    I'm new to crossbows


    Fresh Blood Doesn't meanI'm new to crossbows

    Posts : 7
    Join date : 2010-04-24
    Location : oxford - UK

    Re: Riser Material

    Post by tod on Sun May 02, 2010 3:23 pm

    Interesting looking bow.

    Aluminium comes in a massive variety of grades and behaviours and will work very differently grade to grade. My background is general engineering rather than metal specific so I cannot really quote grades at you.

    Ali bought from a stock holder or your local store is a pretty soft grade that is horrible to use in most applications and because it machines so badly, but it is ductile and does not work harden too easily. This is usually extruded and that goes hand in hand with its properties. Try looking into grades that are T3 or T5, these will machine well and cleanly and be stiff and a little less like working with sliced cheese.

    Ali can be bought in anything from pure that is increadibly ductile and hardly work hardens at all through to spring grades and ultra stiff and ultra hard aircraft grades. Here in the UK some grades are not available for non military applications. Some hardened grades are brittle enough to shatter if you guillotine them.

    You can certainly forge ali and there is no problem with that and it is very easy to anneal but any porosity you see in a casting will stay as porosity. If you have the skill you can forge weld steel or iron down to remove any porosity, but you cannot do that with the ali as far as I know.

    Ali does not really change colour until it is virtually liquid, but if you wish to anneal ali, heat it with a torch and when you drag a piece of wood across the surface and it leaves a black streak then you are there.

    Tod
    avatar
    Pavise
    Dear Friend, You will be Greatly Missed.
    Dear Friend, You will be Greatly Missed.

    Posts : 128
    Join date : 2010-02-07

    Re: Riser Material

    Post by Pavise on Sun May 02, 2010 8:13 pm

    The original poster, William Tell, was asking about alternative materials, apparently because suitable aluminum is not readily available where he is, and if at all, it is prohibitively expensive. And Ivo introduced "forged aluminum" and I introduced forged aluminum horse shoes. Now I am very fortunate to know two of England's celebrated blacksmiths and I am convinced that these tough old fashioned craftsmen, could forge a sword from tin cans if they were challenged to do so, but even with their calloused and skillful hands they always choose and use the most efficient methods and materials for any given job; within the capacity of their forge (shop). Yes, there is no doubt in my mind that they could hand forge a crossbow riser from a chunk of alloy hacked from a wrecked airplane wing spar or even by laminating some of the softer wing skin into a form of damascus.

    Now all joking aside, I think we should stay on course here and think instead about the problems some of us might run into when it comes to readily finding suitable stock for our home-built crossbows. When I first started making crossbows a hundred years ago, or so it seems at times, I could buy some of the most exotic alloys from a place in London where their customer base was perhaps 5 million people. So naturally, they carried a vast range of metals to meet this huge demand. And just imagine their rolling eyes when a punk hobbyist like me would roll up to their warehouse in a rusty Mini looking for "some stuff to make a crossbow prod". "Do what mate?" Was the usual reply. Ask Robin Allen about Dural K sometime too. The stuff that a German invented for the envelope frames of early airships.

    My source of supply here in Western Canada is very much limited too. And unless I am prepared to place a large order for anything the least bit exotic, and pay up front for it, it 'aint gonna happen. So I scrounge what I can from the few manufactures I have built a relationship with, as well as keep my eyes peeled for "crops" (off-cuts) at either of the two only non-ferrous metal dealers in my nearest city. Other venders are, and can be, literally hundreds of miles from someone here in North America and if there is little or no local demand for a specific material, it won't be found there either. And even if I do find what I'm looking for, I generally only have some toe-rag's word as to what it is. Any colour coding indicating alloy or temper is usually well worn off or simply illegible by then.

    Press forging is used where the integrity of the base metal would be severly compromised through what is generally known as "chip machining"; where unwanted metal is removed to arrive at a given shape. Forging and then "coining" in precise dies removes no metal and merely encourages the grain of the metal to flow under enormous pressure. And of course it is possible to cast a riser as is done for vertical bows, but again this is beyond the capacity of the average do-it-your-self-er and besides that, it can be extremely dangerous and I don't recommend it. Undoubtedly this is why we see them machined from billets of 6061 or 7075 that have been age hardened or otherwise improved for the end uses proposed. To be brief: The T5 designation stands for aluminum that has been heated and rapidly cooled during fabrication, such as extrusion or casting, and then artificially aged. T6 means that is has been heated in a sollution and then age hardened; both being rigidly controlled mill processes.

    I like to subcribe to the KISS principal as much as I can. That is: Keep It Super Simple.

    Now back to my sintered metal crossbow riser.

    Pavise
    avatar
    tod
    Fresh Blood

    Doesn't mean
    I'm new to crossbows


    Fresh Blood Doesn't meanI'm new to crossbows

    Posts : 7
    Join date : 2010-04-24
    Location : oxford - UK

    Re: Riser Material

    Post by tod on Mon May 03, 2010 1:36 am

    Malta I don't know about source material but whereever you are I found that a good way to get material is find a fabricator of that material and offer him some cash for raiding his scrap bin.

    North America, 'Metal Supermarkets' does mail order of all manner of materials in whatever size you need so they are a great source for that piece of sheet or or tube you need.

    Walnut is fine, but in Malta I would go for Olive, which looks gorgeous and is hard and dense and readily available. I think the price you were quoted for the ali billet was fine - it is a big piece of metal and at that size it would be some decent alloy. The problem is that you will be throwing away 85% of the metal once you have machined it - so actually the cost of the metal in your riser would be maybe $10 which sounds more reasonable.

    I think you would be on the right track to fabricate it out of pieces like bow shown; it would be a cheaper solution.

    Tod
    avatar
    Ivo
    Admin
    Admin

    Posts : 1041
    Join date : 2009-11-25
    Age : 29
    Location : NJ, USA

    Re: Riser Material

    Post by Ivo on Tue May 04, 2010 6:54 am

    I agree...and as we seem to have swerved a bit from the original path of this post with the original poster nowhere in sight(William Tell, where did you go? ), the list of available materials is only so long, yet the number of ways of making it work for our application is much larger....we are left to further discuss the material properties and it's limits.

    Pavise and Tod have mentioned two very interesting things. I remember arguing with someone on the topic of "wasted material" and at the moment I was exploring lost foam casting process(shell casting) which involved fabrication of the model out of styrofoam that would be invested and cast without prior elimination of the foam model(given foam is burnt out by the hot metal during the cast >>>Link).
    I used the foam block from which I was about to cut out the riser model to illustrate how much material was going to waste if such a riser was to be milled from a solid block of aluminum...ouch.


    Though casting IS in fact a very dangerous practice and I agree with Pavise on it being a somewhat complex controlled process, in my opinion it is about as complex and as dangerous as operating a forge...those of us who can do it, simply have yet another technology at their disposal...those who don't...well - they don't.

    I don't encourage anyone nor am I trying to discourage those who wish to try it. I can only say what I tried and how it went and why. When first attempting the lost foam casting method, I wasn't very successful due to my inability to reach and maintain the 1600-1800F temperature required for successful elimination of styrofoam during such casting process and thus ending up with pores and voids in the finished casting...oh and it was all happening outside in the winter time too.


    With some better equipment such high temperatures can be easily reached/maintained and a rather large melt can be ready in as little as 15 minutes.(More info in the Technology/Metalworking forum) Manufacturers/suppliers like Metal Supermarket even suggest that materials supplied in blocks can be melted down and cast into a variety of complex shapes etc. etc.

    With casting as yet another option, it is still somewhat limited to a set of specific alloys that lend themselves to the process without runing into much trouble later...some of this information can be found in the Wikipedia under "Aluminum Alloys">>>Link

    I wasn't successful in my beginnings, but there was an individual inspired by our arguments who decided "it was meant to be" and went through with casting a riser using the sand casting method. Here is his little "photobucket" - >>>Link

    If not casting, then there is yet another example of what can suffice in a somewhat low to medium power crossbow...though "nuts and bolts" designs don't seem to be very popular due to people fearing that they might loosen from vibrations.



    Yet it doesn't seem to bother Danny >>>here , crazy looking thing, isn't it.






    * *
    ~ "I don't have any special talents. I'm only passionately curious."
    * * *
    ~ "All Genius is Simple"
    * *
    avatar
    Pavise
    Dear Friend, You will be Greatly Missed.
    Dear Friend, You will be Greatly Missed.

    Posts : 128
    Join date : 2010-02-07

    Re: Riser Material

    Post by Pavise on Tue May 04, 2010 10:38 am

    The reason I chose not to promote "casting an aluminum riser" is because I don't want to be held accountable for anything going wrong. That said, I see no reason why the discussion shouldn't continue. And let's see if we can keep it practical.

    But as I read through these various ideas I am reminded of a dear friend many years ago who being keen to enter the emerging sport of Kart (Go kart) racing, decided that rather than subscribe to proven bronze welded tubing for a chassis, he instead used Dexion slotted angle. This was a new steel shelving product being promoted at the time and various home-shop magazines were full of crazy ideas for its use. My friend had made many metal chips and had cut himself several times on this aggressive material before his wife asked me to please talk to him. Thankfully I was able to convince this genious of a man that he was wasting his time, inasmuch as the newly formed sport governing bodies would never let him drive it in the company of others anyway. He then sucked up his pride and went to the extreme and bought one of the very latest Bultaco powered shifter karts and darn near scared himself to death.

    The world of home built crossbows is full of similar stories and I have no doubt that some of them go back hundreds of years too. As dear Robin always says, "Try it mate. That's how we learn." But it is well to remember that personal experience is only truly valuable if one doesn't die in the process!

    I think that it's time for a new Subject heading named "Resources". A place where folk can let us all know what works and where to get it from too.

    Pavise
    avatar
    Ivo
    Admin
    Admin

    Posts : 1041
    Join date : 2009-11-25
    Age : 29
    Location : NJ, USA

    Re: Riser Material

    Post by Ivo on Fri May 07, 2010 3:11 am

    This whole forum is really for informational purposes and everything written in the "Discussion" is to be taken as a discussion - by no means should anything off of internet be taken for a fact, as for "Resources" ...when designing the forum I knew we couldn't go by without such a subforum, so it exists, only under a different name > "Technology". I broke it up into a number of different shop corners like Woodworking, Metalworking, Composites, etc. and have even created a few topics where I planned to gather practical information about different technologies available to an average person, as well as post some How-to topics on component fabrication and such.

    Now I think materials are only roughly a third of the path to achieving success, design goes toe to toe with materials and a great example of such a design related disaster is one of Barnett crossbows. The crossbow is pretty cool with it's quick detach prod and all, but this fella was lucky enough to get away with one broken finger (guess which )...and he was using a cocking string, imagine if he was hand spanning the bow(second photo).

    Off with the horror story... On with the pictures...



    Yet there are crossbows out there that have cast risers that have been shot thousands of times and are still shooting today...bulky, heavy, somewhat ugly, but alive and well.

    Pavise,

    Don't think that I don't agree with you, such a serious load bearing part as a riser should not be taken lightly, considering that when the string comes to a stop the forces multiply by five (if I remember correctly) and every little flaw x5 times more chances of failing.

    Kids stay in school...go to college, university, etc, ...anything, but this VVV



    Pavise wrote:
    I like to subcribe to the KISS principal as much as I
    can. That is: Keep It Super Simple.

    Now back to my sintered
    metal crossbow riser.


    I've missed this one at first, but after rereading the posts >>> "sintered riser" is something that hit me by surprise...this is wicked stuff!

    If this was for real...would you be thinking of something along the lines of Zirconia?

    I send out three dimensional scans and models of prosthetic frameworks(dental) to be milled and sintered in Zirconia and also hear that car engines and high end shark fishing rods have bearings made from the stuff...it would be amazing to see a crossbow riser engineered to match the potential of such material.




    * *
    ~ "I don't have any special talents. I'm only passionately curious."
    * * *
    ~ "All Genius is Simple"
    * *
    avatar
    Pavise
    Dear Friend, You will be Greatly Missed.
    Dear Friend, You will be Greatly Missed.

    Posts : 128
    Join date : 2010-02-07

    Re: Riser Material

    Post by Pavise on Fri May 07, 2010 10:22 am

    Hi Ivo,

    When I wrote about "what works" I was really meaning materials rather than technology, even though the two can be considered together.

    A sintered metal riser would be an interesting project, but without affordable access to such a sophisticated process, it is way over the top for our needs. I was joking.

    There are metal reinforced epoxies available that might better lend themselves to the plasticity of design that we need, and these too can be hand filed or machined to final profiles too.

    And who would have thought that some discarded snow skis might provide materials for a prod? Me! I have made a couple of very functional junior crossbows by taking some old skis and then cutting off the turned up ends and shaping them for the prod limbs. One pair in particular are extremely efficient and yet I have no idea what they're made from. I only know that they were made to flex and return to shape and that's basically what we ask from a prod, right.

    Pavise
    avatar
    Ivo
    Admin
    Admin

    Posts : 1041
    Join date : 2009-11-25
    Age : 29
    Location : NJ, USA

    Re: Riser Material

    Post by Ivo on Sun May 09, 2010 1:59 am

    Yeh I heard about those metal epoxies...also heard that they are a pain to work with(clogging up files and ruining sanding belts) ...metal riser or at least partially made of metal would still be my choice...today is Sunday , So I'm going to see how that fiberglass/resin mix tastes ...also one thing that may seem obvious, but I'm not sure if anyone mentioned this, so just in case - those composite risers definitely need some kind of threaded metal insert to anchor the bolt or otherwise be designed in such a way that the bolt would pass through and have a nut and a washer on the back to keep it from tearing out.

    Sort of like on this one VVV




    To splash something new here...

    There is a very interesting adjustable/collapsible riser that I would love to make one day.



    It is actually a modification of a regular riser like in the above crossbow, only in in place of limbs - pivoting limb pockets were mounted...as I understood the pivoting limb pocket is made of two parts and both are made from steel profile of varying thickness/size. I should have a 3D Model done by the end of the day(the one in the photo is just adjustable and not fully collapsible).
    ___________________

    Skis

    I heard many stories, both success and failure, it seems you are one of the lucky few who actually got a good pair of skis, as it turns out these things are a bit of a surprise from manufacturer to manufacturer, could be cake or could be fish...no body knows.




    * *
    ~ "I don't have any special talents. I'm only passionately curious."
    * * *
    ~ "All Genius is Simple"
    * *
    avatar
    Ivo
    Admin
    Admin

    Posts : 1041
    Join date : 2009-11-25
    Age : 29
    Location : NJ, USA

    Re: Riser Material

    Post by Ivo on Sun May 09, 2010 4:09 pm

    Here are the promised goods ... Lots of machining, but this is a modification and not a scratch built riser, so I'm sure it can be simplified. The materials for this one can be steel profile and the biggest one would probably be the steel riser block, prior to machining (if made a little slimmer) would measure around 1.5"x4"x.75" - the original riser block is only four inches because it was meant for mounting an all-fiberglass solid bow(joined in the middle that is Smile )

    Download Google Sketchup 7 if you wish to view/measure this model...>>>Link (yes it's free and easy to use)



    PS: Make sure that in your Profile > Preferences -> "Always allow HTML :" is set to "Yes" to be able to view the riser model ...Have fun and don't forget to post what you think about this riser.




    * *
    ~ "I don't have any special talents. I'm only passionately curious."
    * * *
    ~ "All Genius is Simple"
    * *

    Sponsored content

    Re: Riser Material

    Post by Sponsored content


      Current date/time is Mon Aug 21, 2017 7:34 pm