[Kornphlake]

yeah, it would do that but the rigidity of the carbon wouls take 3/4 of the load from the bolt i am guessing.
its going to fit tight like hammer in, then bolts to tighten the wedhe to no slop.

the backside needs a radius so there is not a sharp corner next to the
carbon.

I guess you are probabally right, I think of carbon fiber as strong in tension and compression but flexy under lateral loads, even though I know parts like handlebars are really stiff, I tend to think of carbon more like a fishing rod. If you were making the part out of two similar pieces of metal I'd think of it differently.

I recently had a senior engineer explain that I needed to add more material to a v shaped die I was designing to keep it from spreading out, for some reason I was thinking, "hey this is metal it doesn't break or bend because it's thick and it's metal" when realize you've got an 80 ton press pushing on it you start thinking about metal a little differently. I guess you could always add material around the joint to beef up the carbon and keep it stiff just like you would if it were metal or wood or nacho cheese.

 

[Biscuit]

I'm liking that a lot more.

Now lets see the frame interface!


You know, you may want to radius the top and bottom edge of the dovetail. I'm imagining at the steepest setting, it will stick out of the frame a bit.

 

[alexchannell]

no, i have it right, its 1.95. the od of a 1.5 fork steerer is 1.5.

Damn...I was totally thinking of the wrong thing..oops.

 

[dazz]

even drilling the holes with an end mill they will walk?
might be able to space them out.

yes, its to scale, 1.5 headset and E13 adapters are about 2''.
bolt holes are 8mm.

An idea to reduce the number of holes required:

With a bit of clever hole spacing, you could have two head angle settings one way (say 66 & 64). Then you turn the head tube upside down & use the same holes to get 65 & 63 degrees.
Only problem with this is that it would mean removing the forks & headset for half of the head angle settings.

 

[ÆX]

An idea to reduce the number of holes required:

With a bit of clever hole spacing, you could have two head angle settings one way (say 66 & 64). Then you turn the head tube upside down & use the same holes to get 65 & 63 degrees.
Only problem with this is that it would mean removing the forks & headset for half of the head angle settings.

i was thinking about that today. can you sketch it for me?

then my holes could have material all around then instead of overlaping

 

[allsk8sno]

I would think your current design would lend itself to ovalization of the holes think about the cycle of hits that interface would take. the previous mentioned idea of having material between the holes would be the best solution, or possibly using multiple bolts. if i get bored maybe i'll run something on this, though i mostly do static analysis/testing, i would love to see the results of the FEA run though

pete

 

[OGDMFG]

hey alex I like the new thought process, I would probably take the sharp corner out of the bottom of the vee, , what do you have in mind for the mating pieces.

jeremy

 

[ÆX]

hey alex I like the new thought process, I would probably take the sharp corner out of the bottom of the vee, , what do you have in mind for the mating pieces.

jeremy

thnks, but these guys have had some good ideas that
is why it looks like it does.

here is a working flip 66-63

mating pieces? the carbon main frame?

 

[dazz]

here is a working flip 66-63

That's spot on what I was thinking, you don't need me to sketch it now. This is pretty cool, seeing the development of this concept in real time with input from people at opposite sides of the world!

 

[Kornphlake]

That's spot on what I was thinking, you don't need me to sketch it now. This is pretty cool, seeing the development of this concept in real time with input from people at opposite sides of the world!

When do I get my dividend check?

 

[Cave Dweller]

I liked the initial design you had BCD and was even thinking about one in the future, but its getting too complicated now. 5 degrees for head angle, multiple shock positions, 26-29 inch wheels. More adjustment just means more things to tune wrong.

I would go and see an engineer. I thinks its great getting input from riders about geometery and so forth, but its a huge worry that you are asking riders on a forum about what size bolts need to be.

 

[dazz]

When do I get my dividend check?

I'll be waiting for mine too! I bet they end up lost in the mail... that always happens.

 

[ÆX]

I liked the initial design you had BCD and was even thinking about one in the future, but its getting too complicated now. 5 degrees for head angle, multiple shock positions, 26-29 inch wheels. More adjustment just means more things to tune wrong.

I would go and see an engineer. I thinks its great getting input from riders about geometry and so forth, but its a huge worry that you are asking riders on a forum about what size bolts need to be.

well its down to 4 head angles 63-66.
the shock mount areas are for 9.5 p-p for 26ers
and 8.5 p-p for 29ers to keep the same bb and head
angle. the holes to the back of the bike make it
more progressive middle is linear forward mounts
is progressive for air shocks. there will be small adj
plates, not the big ones you see above
the render above is not final, its just
where i want them able to move to
so i can see my clearance issues.

what you are seeing in this thread all aspects
of its design phase. something i do myself
generally but need input now so i have
come to a place i am welcome and
people like to help.

a lot of these guys ARE engineers.
i am smart i just don't want to
over build, i want to build right.
this is what any large company
would be doing, the designer working
with engineers to come up with a
solution. its just these guys are helping
free, well i might help them out some
later down the road.

don't give up faith yet. lthumbsdown:

O, by the way every bcd comes with
i booklet on how to dial you bike for
the track and my home phone number. lol

 

[ÆX]

Damn...I was totally thinking of the wrong thing..oops.

updated. i went to a 50mm width for 1 1/8.
41mm headtube ID for cane creek IS headsets.
i just can't fit a 60mm wide headtube for 1.5.

moved bolts to a thicker area, better?
can you see anything less before we
look at the FEA

bcdracing.com/psycho-billy-cadillac/mar/headkeyv.SLDPRT

 

[Kornphlake]

radius the concave corners, at the point of the vee and the corner at the edge of the vee closest to the headtube bore. Sharp corners are your enemy.

 

[ÆX]

radius the concave corners, at the point of the vee and the corner at the edge of the vee closest to the headtube bore. Sharp corners are your enemy.

the tool i am cutting with would be a 3/4 drill point end mill.
is it possible to hand radius the point of? should be huh.
the other edge i could do with a ball end mill and leave
that edge alone.

 

[xy9ine]

O, by the way every bcd comes with
i booklet on how to dial you bike for
the track and my home phone number. lol

i love the micro builders. talk about personalized customer support; nothing like being able to call up the guy who designed & built your frame. fun watching the design process. lots of neat ideas going on - can't wait to see the finished product.

 

[pterodactyl]

I like the idea of using a design where you rotate something machined eccentrically to make an adjustment like this. The 303 does that in the upper pivot ( I had one and loved how easy it was to adjust). Mindbomb (yeah, I know) and a couple others did something where they adjusted the head-tube. What about this:

Slot the head tube so that the areas where the headset bearings can be tightened (clamped) and loosened,

Make a cup that the upper set presses into that is milled spherically on the outside and mates with a spherically milled surface inside the head-tube (think ball-socket joint).

There must be a way to rotate an eccentric on the bottom bearing area that will adjust the angle and not skew the front wheel left or right. I can't think of it. An alternative could be spacers that are C-shaped on one side to ride againt the face of a cylindrical cup you would make for the bearing and tennoned to go into a groove in the down-tube area.

This way, only the angle changes, not the height of the bars.

I can just see how a person would have a screaming match at his bike trying to adjust the angle of the head-tube with his Park bike stand in the parking lot at Plattekill. He would have to support the whole front end after the bolts are out, then line up the right holes and push it back in, all the while dropping a bolt or two in the dirt followed by spilling his beer.

Or I might be full of crap and should get back to work.

Very cool thread either way.

 

[ÆX]

I like the idea of using a design where you rotate something machined eccentrically to make an adjustment like this. The 303 does that in the upper pivot ( I had one and loved how easy it was to adjust). Mindbomb (yeah, I know) and a couple others did something where they adjusted the head-tube. What about this:

.....

This way, only the angle changes, not the height of the bars.
.....

it would also raise the front wheel up and down from ground level
changing you bb heights.

i can picture the ball socket things you had in thour post but it
would be hard to make from carbon.

this will be simple to adjust. take two bolts out mallet hammer
up or down, then re-bolt. for the other two adj you have a second
headtube that you put on so you don't have to hammer headset
cups out. a pre flipped on ready to go.

thanks for the input i am about there i think.

 

[Westy]

Aren't there headsets out there, King comes to mind, where the upper and lower cups/races are identical? The logo would be upside down but the function would be the same.

You'll need to come up with an vertically mirrored BCD headbadge.

 

[pterodactyl]

Nevermind...like Commencal.

It snowed here in Buffalo today.

 

[ÆX]

Aren't there headsets out there, King comes to mind, where the upper and lower cups/races are identical? The logo would be upside down but the function would be the same.

You'll need to come up with an vertically mirrored BCD headbadge.

might be i haven't checked that yet.

i have my stickers made like that, then they drape over
the top tube. i like'm.

the headtube will be alum so maybe I'll get fancy and cnc
a logo in there, something raised and polished like vanillas.

NAHBS watch out!

 

[Kornphlake]

the tool i am cutting with would be a 3/4 drill point end mill.
is it possible to hand radius the point of? should be huh.
the other edge i could do with a ball end mill and leave
that edge alone.

You could grind the edges of the flutes on your tool to get a radius near the headtube. I can't remember if it's possible to grind the point on an endmill without messing up the cutting edges at the very center. Unless you've done a lot of grinding I might pass on that one. You could always cut it with the vee shaped mill then make a light pass with a ball endmill down the root of the vee. You don't need a huge radius, .125 or even .0625 should do the trick, if you've got a tool maker friend he'd probabally be able to grind a tool that would do everything with one pass.

 

[Westy]

You could grind the edges of the flutes on your tool to get a radius near the headtube. I can't remember if it's possible to grind the point on an endmill without messing up the cutting edges at the very center. Unless you've done a lot of grinding I might pass on that one. You could always cut it with the vee shaped mill then make a light pass with a ball endmill down the root of the vee. You don't need a huge radius, .125 or even .0625 should do the trick, if you've got a tool maker friend he'd probabally be able to grind a tool that would do everything with one pass.

Could also use the pointed endmill to make a pass at each wall at the final wall spec but not at full depth then take a pass with a ball mill to cleanly bring the two walls in at a nice radius.

 

[ÆX]

Could also use the pointed endmill to make a pass at each wall at the final wall spec but not at full depth then take a pass with a ball mill to cleanly bring the two walls in at a nice radius.

thanks guys, think i should carry radius of the head tube around
and knock off the sholder?

 

[lorant]

I really have to agree - discussing the design openly and actually being able to see steps and decisions is very confidence inspiring.

There's just one little suggestion I'd make (I am by no means a mechanical engineer) - the two sharp edges where the cut-out triangles meet the shoulder near the steerer hole would seem to have high stresses, especially as I would think most stresses of the fork would enter nearby (into the steerer hole surface near there)... the attachments says more I guess Anyway, I think that'd be one of the most-stressed areas now that the bolts are relieved by the dove-tail.

My first post btw Great forum and even better thread

 

[alexchannell]

thanks guys, think i should carry radius of the head tube around
and knock off the sholder?

It's looking better, the round in the V is pretty much mandatory. There are a few ways to do that. Grinding the tool is one, but unless you do it very well, you will end up with a poor finish on your part. I would just take a ball end mill of diameter .25 or so, and go just deep enough to cut out the sharp V.

I'm glad you took the suggestion of having the bolt holes seperated a bit. However the location won't work very well.

Ohh and make sure you have fillets (rounds) on that sharp inner edge on the head tube.

You want the V in the frame to clamp into the V of the headtube. If the bolts are all the way back there, you are basically fighting against a lever and will loose tons of clamping force. The center of the V (where you had them before) is really the best place. You want the fictional forces to take as much load as possible and prevent the bolts from seeing shear loads. Seeing sheer loads is what will ovalize your holes.

I would also suggest you use shoulder bolts or similar for the clamping. Or at least have bolts where the threads don't ride on any shear surface. (The threading on steel bolts loves to damage soft aluminum).

 

[Kornphlake]

Leave the shoulder, I think you'll want all the surface contact you can get. Just add a fillet where Lorant pointed. I agree with the above post saying the bolt holes should go farther forward, in the vee. If you drill the holes first then cut the vee you won't have many problems with the drill wandering, you may even be able to use the drilled holes to fixture the part for machining the vee shaped slot.

 

[Kornphlake]

One more feature you could add to lock everything together would be a vee or notch of some type along the curve on the back side, you could get some more surface area and relieve a little bit of shear stress on the bolt. I'm not sure how you plan on laying the carbon fiber though, adding to many features may make it impossible to seperate the frame from the mold.

 

[alexchannell]

One more feature you could add to lock everything together would be a vee or notch of some type along the curve on the back side, you could get some more surface area and relieve a little bit of shear stress on the bolt. I'm not sure how you plan on laying the carbon fiber though, adding to many features may make it impossible to seperate the frame from the mold.

I like the idea of a dovetail like thin on the backside, that would be very challenging to machine however.

 

[ÆX]

I like the idea of a dovetail like thin on the backside, that would be very challenging to machine however.

i would do the whole concept in negative if i though i could machine it.
you are right w/o a 5 axis it would be hard do do an undercut.

 

[ÆX]

I really have to agree - discussing the design openly and actually being able to see steps and decisions is very confidence inspiring.

There's just one little suggestion I'd make (I am by no means a mechanical engineer) - the two sharp edges where the cut-out triangles meet the shoulder near the steerer hole would seem to have high stresses, especially as I would think most stresses of the fork would enter nearby (into the steerer hole surface near there)... the attachments says more I guess Anyway, I think that'd be one of the most-stressed areas now that the bolts are relieved by the dove-tail.

My first post btw Great forum and even better thread

thnks, i'll work on that. you come from the frame forum?

alex

 

[ÆX]

here is some stress analisis i was trying.

not too sure what i am doing.

fixxed at two bolts only, worst case.

load at the end of a 22.5in "fork"

: updated : http://www.bcdracing.com/psycho-billy-cadillac/april/head-1k-forward-2bolts.avi

 

[HaveFaith]

Hey Alex, nice posting the FEA. What kind of constraints do you have going on the headtube portion, other than the bolt hole contstraints? What you should do is place cylindrical supports for the bolt holes, and on the surfaces where the frame clamps, put a compression only constraint. If those surfaces are fully constrained (which is what it looks like in the vid) then you wont get an accurate reading. What you can also try doing is making a separate tool piece, that mimics the frame and make it beefy enough to have infinite (close to) stiffness, and use that as a constraint for the head tube.

Also, what kind of loading are you putting on the end of the fork?

If you have any kind of questions on FEA or engineering in general, Id be glad to help where I can...

 

[ÆX]

H...........

infinite (close to) stiffness, and use that as a constraint for the head tube.

steel aisi 304? whast the strongest?

Also, what kind of loading are you putting on the end of the fork?

1000lbs forward on the end of it.
i couldn't fig how to do this to an assembly so i just
extruded out a solid. how do i know when failure occurs?
any change in color, please exsplain. this is what i get
for no schooling.

its just 6061. two bolts.

i updated the link with a new one.

 

[luelling]

I just wanted to ask, why not do a headtube like my Scott High Octane? I have several months on the frame and I have no movement in the headtube piece. I was a bit worried when I received the frame, but it has worked out. Just a thought....maybe a combination of the slot headtube with wrap around mainframe and bolts? I'm a software engineer, not mechanical, just thought I would share those thoughts.

 

[ÆX]

I just wanted to ask, why not do a headtube like my Scott High Octane? I have several months on the frame and I have no movement in the headtube piece. I was a bit worried when I received the frame, but it has worked out. Just a thought....maybe a combination of the slot headtube with wrap around mainframe and bolts? I'm a software engineer, not mechanical, just thought I would share those thoughts.

well i am needing to bolt an aluminum headtube to the
carbon for production simplicity. layup on a carbon headtube
is difficult and if i am machining a headtube anyway i might as
well make the carbon connection simple, that and mine ARCs ABOVE
the front wheel too keep the bb height the same. it makes
a big difference in keeping the geometry simple for the customer.

i think a lot of the early mass adjustment bikes were so complicated
that a lot of people got lost and ended up not liking all kinds of
options b/c they change one thing and it throws off another.

this bike will have independent BB height and
shock rates. 29 or 26 w/o a geo change.
head angle will lengthen wheelbase but generally
when you want slack you want long too. when
want steep you want short. i also want to
make a long headtube that stick forward 1.5
more for the tall humans.

 

[alexchannell]

H...........



steel aisi 304? whast the strongest?



1000lbs forward on the end of it.
i couldn't fig how to do this to an assembly so i just
extruded out a solid. how do i know when failure occurs?
any change in color, please exsplain. this is what i get
for no schooling.

its just 6061. two bolts.

i updated the link with a new one.

It looks like you're using COSMOS Express? It won't do assemblies and is really limited on FEA constraints you can put on it. Upload the files you have and I'll put together an assembly with all the friction, bolt torque, mounting point etc. It would also help to know how it attaches to the carbon (picture would be best).

 

[ÆX]

It looks like you're using COSMOS Express? It won't do assemblies and is really limited on FEA constraints you can put on it. Upload the files you have and I'll put together an assembly with all the friction, bolt torque, mounting point etc. It would also help to know how it attaches to the carbon (picture would be best).

yes, express.

here is the part. look at the revolve cut sketch to see where
the carbon would go.
i have yet to cut the neg of that cut to the frame.
hard to align it up.

www.bcdracing.com/psycho-billy-cadillac/april/headkeyv.SLDPRT

 

[alexchannell]

yes, express.

here is the part. look at the revolve cut sketch to see where
the carbon would go.
i have yet to cut the neg of that cut to the frame.
hard to align it up.

www.bcdracing.com/psycho-billy-cadillac/april/headkeyv.SLDPRT

Good deal, probably will take a hour or two to do the FEA.