Direct Drive #219 Pitch Monster Sprocket

[etard]

I have been talking to a couple of machine shops about making a batch of jumbo #219 rear sprockets and am making some good headway. I have been telling them there is a small niche market for 2 or 3 dozen sprockets made from Delrin in sizes not available currently. If I can get the ball rolling on this I would like a head count on who would be interested, how many ( buy some extras :wink: ) and what size would be preferred. I was thinking somewhere around 150-170 tooth. Give me some feedback guys, I don't think anybody else has done this yet. Also, what would be a fair price for something like this?

 

[recumpence]

E,

I am open to taking a couple to mess around with.

Also, I am willing to help fund this if you need that. This is a great idea. Delrin is good material to work with. You could also get a few done in aluminum as long as they were highly hollowed out to save weight.

Matt

 

[Miles]

170t would be about 16" in diameter

It might make more sense to use a large diameter aluminium mount/adapter....?

 

[deecanio]

etard,

they'd also have to be dirt cheap as my 80t composite extron only cost me £5
that said i may take one

D

 

[spinningmagnets]

I was curious, Delrin sounds like interesting stuff...

http://cncplastics.com/acetals.htm

"...Continuous service up to 180 F (82 C)
· Available in sheet, plate, rod and tube
· Available in white and black (standard colors)
· Low moisture absorption
· Excellent in submerged or wet applications
· Excellent strength and stiffness
· No centerline porosity in Acetal copolymer
· Wide product size range up to 8.0” Thick
· Easily machined
· Glass fiber filled grades for improved strength and stiffness

Acetal (Brand name: Delrin) provides high strength and stiffness coupled with enhanced dimensional stability and ease of machining. As a semi-crystalline material, Acetal is also characterized by a low coefficient of friction and good wear properties, especially in wet environments.

Because Acetal absorbs minimal amounts of moisture, its physical properties remain constant in a variety of environments. Low moisture absorption results in excellent dimensional stability for close-tolerance machined parts. In high moisture or submerged applications, Acetal bearings outperform nylon 4 to 1. Acetal is ideally suited for close tolerance mechanical parts and electrical insulators which require strength and stiffness. It also offers resistance to a wide range of chemicals including many solvents.

Advanced Industrial offers both homopolymer and copolymer grades of Acetal including enhanced bearing grade materials. Our standard Acetal that we stock is a porosity-free Acetal and offered as our standard general purpose grade. For improved frictional and bearing properties, PTFE (Teflon)-enhanced Delrin AF products are available..."

 

[etard]

170t would be about 16" in diameter

It might make more sense to use a large diameter aluminium mount/adapter....?

I was gonna get it drilled out to fit disk brake mount, gary's adapter, matt's adapter, sickbikes freewheel, a go cart hub, and / or any combination of the previous. :?

Right now I am more concerned with the price. How do they make sprockets anyway? I was thinking about how guys use drill presses to cut round holes, and I thought how you could find the right drill bit and drill out every tooth and then using band saw to cut a rough outside circumference, then lathe off the teeth to size, length and width. I have access to all those tools so if I don't get the right price quote, I may attempt this on some sheets (.25"?) screwed together. Labor intensive, but if done right the results could be priceless for direct drive. If someone knows a better/easier/ more elegant solution please post, I'm just shootin from the hip here.

D,
Even if it cost $25-40 it would be well worth it to get the extra torque from faster spinning motors.

Matt,
Not trying to step on any toes here, this could never replace the beauty of your drives, I just think less moving parts is always better. What kinda power could I expect from a sprocket mounted on a 24-26" rim? With that many teeth you could spin the motor up pretty fast!!

Miles,
How many teeth would a 26" sprocket have? Hmmmm. Do you have a resource for sheets of Delrin? And is there a certain grade or hardness I should be looking for?

 

[enoob]

i like the idea . i suspect your going to want to look at something like miles has mentioned to get price down though . to make it out of all derlin will probably mean machining out of a thick sheet at least 16" x16 " . the cheapest i found the stuff up here was $75 a square foot for 3/4 inch thick sheet .

i do believe you could make the sprocket yourself especially if you have a decent drill press, a band saw would help and yes it will mean some work its just getting the material at a good cost that will be your headache.

 

[etard]

 

[Thud]

266t Etard :lol: thats superextream
100+ inches of 219 chain$$$$$$$$$$$$$$$

We need a better suply of 219 primay's 10-18 tooth. I been contemplating making a hob to cut some. Just dont know if there is really a market for them.

 

[Miles]

How do they make sprockets anyway? I was thinking about how guys use drill presses to cut round holes, and I thought how you could find the right drill bit and drill out every tooth and then using band saw to cut a rough outside circumference, then lathe off the teeth to size, length and width. I have access to all those tools so if I don't get the right price quote, I may attempt this on some sheets (.25"?) screwed together.

If you truncated the tooth profile enough, you could make a sprocket by drilling an array of holes...

 

[liveforphysics]

Delrin is a fantastic material. My pitbull would always shred any commercially available dog chew toys in a day or two, and I think he was eating the pieces as well...

I cut some delrin into bone shaped chunks on the bandsaw for him, and he has been able to mess them up, but still have never been able to chew through one yet, and it's not for lack of trying.

Delrin is not cheap. Be ready to have a substantial materials cost.

You could keep costs low if you did an aluminum hub, and divided the toothed section into 4 pieces that each covered a 90deg stretch around the sprocket, and bolted this 4 piece outside toothed edge to the aluminum hub. That would let you use perhaps 1/3rd of the delrin, still provide a quiet tooth/chain interaction, and have the benefits of a cheap and rigid aluminum center hub portion.

 

[Miles]

You could keep costs low if you did an aluminum hub, and divided the toothed section into 4 pieces that each covered a 90deg stretch around the sprocket, and bolted this 4 piece outside toothed edge to the aluminum hub. That would let you use perhaps 1/3rd of the delrin, still provide a quiet tooth/chain interaction, and have the benefits of a cheap and rigid aluminum center hub portion.

Yes, I think this would be the way to go for large diameters - if you need to use plastics.

 

[deecanio]

etard,

i didn't mean to poo poo your idea i just thought it might become a very expensive thing to make along with the price of the chains as Thud mentions.
That said lukes ide would bring costs down and then i'd have to ask this question...
if the 266t ~#219 became a reality and it was run directly by a 11t (just for example) that would give a 24-1 reduction soooo would that work just as well as using the reduction on matts drive??
by that i mean does the method of how you achieve the reduction make any difference to performance?

D

 

[Miles]

by that i mean does the method of how you achieve the reduction make any difference to performance?

Of course - the efficiency will differ....

 

[Miles]

We need a better suply of 219 primay's 10-18 tooth. I been contemplating making a hob to cut some. Just dont know if there is really a market for them.

I'd say there soon will be...

 

[deecanio]

Of course - the efficiency will differ....

worse with direct drive miles?
is it a viable option in your opinion?

D

 

[Miles]

Achieving the reduction in a single stage is usually more efficient.

 

[deecanio]

ok etard im in !!!
Miles if the sprockets were made could i use one with direct drive and only have a 3220 and this proposed sprocket?
if 266t is too extreme then maybe a smaller version.
D

 

[Miles]

if 266t is too extreme then maybe a smaller version.
D

As Thud said, 266t would be about the diameter of your wheel

 

[Thud]

240t = 23.376" (593.7mm)pitch dia. still quite a cog......

 

[Miles]

Miles if the sprockets were made could i use one with direct drive and only have a 3220 and this proposed sprocket?

Sure. What happened to stealth?

 

[drewjet]

If your getting sprockets made, look into 12 tooth 3/8 shaft to fit the astro. I have been looking and getting nowhere.

 

[deecanio]

stealth is losing over ease of install and simplicity
23" sprocket is tooo big, but im all for exploring bigger than 92.
would it be possible, rather than use ally for the body of the adapter to use transparent plastic?
drewjet i think Gary was looking at some drive sprocket options.

D

 

[Miles]

I think 15:1 would be a sensible reduction to achieve in one stage. So, you could run a 3220 at around 4500rpm and still achieve more power than from a 3120 running at the nominal speed.

 

[liveforphysics]

stealth is losing over ease of install and simplicity
23" sprocket is tooo big, but im all for exploring bigger than 92.
would it be possible, rather than use ally for the body of the adapter to use transparent plastic?
drewjet i think Gary was looking at some drive sprocket options.

D

As long as you leave enough meat in the center of the aluminum sheet to keep from tearing out the hub mounting area, you can cut the rest of it to feature something like 8 1cm wide radial spoke pattern cut into it to connect to a thin outside rim that the 4 pieces of delrin are affixed upon.