Anybody here that can make a gear???

[ezman604]

This is something I've never tackled. But with the machinests we have here, one of you might be able to handle a small job for me if you are willing. I have a semi-professional shredder. It is larger than a home 6 page shredder but smaller than the 4' commercial model we have at work. It's an in between size. It is belt driven and a nice older unit. It has a damaged main gear though. It's made from a nylon type material, possibly phenloic. I guess I could use an aluminum gear instead.
The unit was a Chinese model that was discontinued a few years ago and I searched high and low for replacement parts. No-go. The inner (smaller) drive gear is missing 3 teeth. I have molded and poured high strength epoxy to fill the gap that worked for a while. But it does break again. So I need to have a new gear made if I hope to revive this shredder.
Anyway, the gear is less than 4" OD with a gear about 1-1.5" in diameter in the center. Main gear and the smaller center gear are about 1/4" thick each. So entire gear assembly is around 1/2" or a little more in thickness. I need to pull the gear one more time to take pictures and REAL measurments if anyone has the capability and time. I would GREATLY appreciate it and gladly pay for this gear to be fabricated. I will ship the damaged gear to any of you that can tackle such a project....PLEASE!!!!
Kinda like this...not exactly but similar in that it's a dual gear assembly. Let me know by posting here or just send me a pm or email.
MANY thanks ahead of time.



 

[michaelthomas]

You might check on the sdpsi website.  If you know the pitch......they probably have what you need.  It may require some one to mate two gears......but that's not so bad.

Mike

[Rescue35]

There are places that sell gears in bar form. Just turn down and bore for a shaft. Let me break out the computer to find some links.

[Roadworthy]

Dave,

Here's the site Mike mentioned:  https://sdp-si.com/eStore/CoverPg/Gears.htm

[Rescue35]

Here is the site MichaelThomas was referencing. https://sdp-si.com/eStore/Catalog



Here are some others.
http://www.qtcgears.com/
http://www.wmberg.com/products/Spur-Gears-Stock.aspx
http://www.grobinc.com/coldrolled/cust_gears.htm

[ezman604]

Excellent info. Will pull my gear and make some measurements. Looks like the plastic spur gear would be the best thing. Buy the large one and smaller inside one. Bore both to the shaft size I need, slip them onto a shaft, cement them together, drill and insert 2-3 lock pins. Might make this work.

Thanks for the info folks!!!
Bookmarking those sites.

[ezman604]

Finally had the time to tear this beast back down and pull the gear. I looked at the site and cannot match it up. Still need help finding or making this one.



OD of the main gear is about 5". Or more exact 4.949".
80 teeth main gear.
Main gear thickness 0.675".
Hub is 1.065"



OD of the inner gear is 1.9" with 23 teeth.
Thickness is 0.630".



Main gear is fine. Two teeth missing on the inner gear. So my thoughts are if I can locate an inner gear, I can slice the old one off and mount the new one to the main. I can pin and glue or even screw the new one on. I'll find a way.

Any help finding the right gear would be appreciated!!!!

[toine]

Not a machinist here, but I have some hobby level experience in making molds...
Does that gear have a 'match' at all? If so, based on the size of it, you may be able to make your own mold and just pour your own. Smooth-On has a great little beginner kit that has everything you need for trying it out.

[ezman604]

Well, not had very good luck molding. I did mold using the highest tensile strenght epoxy I could lay my hands on. Repair mold lasted a bit but not long enough.
Thanks, I'll take a look at their molding kit.

[michaelthomas]

I would search for a 12 diametrical pitch, 14 1/2 degree pressure angle gear.......that is my best guess based on what you have listed for info and the picture.

The big gear actually looks like a toothed pulley to me.  Maybe HTD or GT tooth profile based on the appearance.

Does the big gear mate to another gear......or to a  belt? 

The tooth profile is not anything close to an involute gear form from what I'm seeing.......that's what makes me think pulley.

Mike

[ezman604]

Thanks Mike. Indeed the outer gear is the drive gear. Mates only with the drive belt. The inner gear mates with two other gears of the knife roller assembly.

[michaelthomas]

Dave.....if you cannot find something ready made, you may want to look into Georotic Motion software.  It used to be pretty cheap.  Seemed like there was a trial version available at one time, too.  The same guy that developed Mach 3 CNC control came up with it.  You could design your gear in the software (really easy), then export a STL file that could be 3D printed by someone.  Lots of guys have 3d printers these days......even high schools that have them will typically print things for free as projects for their student.  Our high school does this, anyway.

Mike

[Roadworthy]

I hadn't thought of it before, but you could probably use the lost wax process to cast the appropriate gear in brass perhaps.

[SeanMP]

When I get home in 5 days I will look at my collection of cutters. If I have something that might work I will hob the gear for you.

[ezman604]

Thanks Sean. Any help is very appreciated. In the meantime, I have a buddy at work that is CAD capable. He has done a lot of work in designing widgets. He is going to create a file I can send off to a 3D printing business to get an estimate. That will be my backup plan.

[ezman604]

MAN, had no clue one 5" gear would be that much trouble or expense. I was able to get a CAD drawing of it. Sent it off to three places for an estimate. One said no, one said $625 and a third wouldn't even GIVE me the cost estimate. Said I would be better off looking for a local jobber. Sure hate to toss this shredder but getting closer to the reality of it.

[mobilehomer]

This may be redundant, but did you try Google for "paper shredder gear", then looking at images? I just saw some thay looked close. You may need to input model number.

[ezman604]

Yep, searched for shredder gear(s), CCS500 Achiever gears and all kinds of gears. No luck. I've about decided to get some mold making clay, make me a mold and pour high strength epoxy. Worst it will do is fail.

It's really rediculious what they want to make a gear, even with me supplying the 3D file. I'm not CNC familiar but seems you can load this file and just toss a chunk of nylon or other heavy duty plastic in a machine and cut it. Oh well, must be lots more to it than that for the crazy prices they want for 1 gear. Also about ready to but me a 3D printer. Sould be cheaper for SURE!!!

[Big Bore Bart]

   If you do mold your own, use some milled glass fiber in the mix, it will double the strength or better.

[Roadworthy]

Dave, if you already have the CAD file, see what it would take to have the gear printed.  3D printers are becoming pretty common.  I don't know that a printed gear would have adequate strength bit it's a thought.