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3D printed bevel gear

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Gordon

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Is there a program to generate a 3D printed bevel gear. I have an old Sears band saw and it has a small bevel gear about 2" dia. I have found a drawing of the gear and I have a 3D printer but my CAD expertise is not up to drawing the gear. I thought perhaps there is a stand alone program to do this.

Gordon
 

RM-MN

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I don't have much CAD experience but I do a little mucking about with FreeCAD. There is an addon that generates gears, also free. There is a section just for bevel gears so if you want to download FreeCAD, there is an add on manager in the tools tab that lets you add the gear generator.

What CAD have you used? There may be a bevel gear generator built in.
 

johnmcc69

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Hi Gordon, there are a few sites out there where you can input your gear criteria & it will create the CAD model for you & allow you to download it in various 3D formats. I've only used them as "representations" in my CAD modeling, so can't vouch for their accuracy...

But, if you send me the specs, I'll model it up for you in 3D CAD & give you a usable (modifiable) printer file.
-I have more faith in creating some models from scratch, & "Machinery's Handbook" has never let me down..

John
 

jkimberln

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I think you could find what you want at Thingiverse. You could look for a program written in OpenScad as it would be variable in a number of parameters. That way you could get the size, number of teeth, angle, etc. that you need. Thingiverse has a large number of gear files.

JerryK
 

dsage

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Gordon:
Have a look on McMaster Carr or one of many Gear suppliers. If the gear you are looking for exists you can usually download it as a CAD file to suit your program and it will be accurate. Once you have the CAD file you can export it easily enough with your CAD program to STL format and then you should be able to simply (?) print it on your 3D printer (with all that is required in that effort i.e slicing etc. ect).
There is a possibility you'll find the gear tooth pattern and size you require but it has a boss or maybe the wrong hole size or something. But editing it with the CAD program to suit shouldn't be too difficult.

The other issue to consider is - Will the gear will be durable enough made from plastic.
 

Henry K

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I had a Sears table saw years ago. My wife's uncle used it once, tilted the table and broke teeth off the gear. In his defense, it required a lot of stress on the gear to tilt the table even though it was working properly - a design problem. Since 3D printed stuff is frequently 70 % air I doubt it would work unless you set the printer to be nearly 100 % plastic and even that may be a stretch.
 

Gordon

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I have looked at several distributors of bevel gears with cad drawings. It appears that this gear is kind of an oddball. It is 16 pitch with 28 teeth. The original was plastic so that should be OK. The original lasted for probably 40 years with light home use. A couple of years ago the gear stripped and I could not find a replacement so I kind of cobbled a replacement in brass using large and small diameter and cutting with a gear cutter with the gear set at an angle and indexed on a rotary table. That seems to work but is noisy. At that time I did not have a 3D printer so the machined version was the only option. I recently had to replace the tires and I had to tear the machine apart so I thought that this would be a good time to make a new gear. Parts from Sears are no longer available.

I have played around with Free Cad in the past and I have found the add on but I have to reeducate myself on how to use Free Cad. I will keep trying.
 

awake

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As someone who has machined gears out of plastic, and has 3d printed gears in plastic, I can offer one person's first-hand experience: the printed gears do not hold up well, while the gears I've machined out of plastic have held up just fine.

My experience is based on 3d-printing gears out of ABS and PETG, with many variations of perimeter and infill settings and different layer heights. The gears in question have been module 2 gears (so, somewhat larger - not tiny) and experience a fair bit of stress. Infill has not been the problem; rather, the teeth strip too easily. I have attempted to 3d-print these gears out of nylon, hoping they would hold up better, but have not been successful in keeping the nylon print from warping. (One of these days I'll make an enclosure and try again ....) I also have some POM filament (trade name Delrin), but it warps even more than the nylon, so again, waiting on an enclosure.

Obviously there is success to be had in some applications, since many 3d extruders use printed gears. It may be that have succeeded even with gears undergoing a greater stress than in an extruder, and if so, I will be very eager to hear about it - I'd like to know how to achieve success!
 

Gordon

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As someone who has machined gears out of plastic, and has 3d printed gears in plastic, I can offer one person's first-hand experience: the printed gears do not hold up well, while the gears I've machined out of plastic have held up just fine.

My experience is based on 3d-printing gears out of ABS and PETG, with many variations of perimeter and infill settings and different layer heights. The gears in question have been module 2 gears (so, somewhat larger - not tiny) and experience a fair bit of stress. Infill has not been the problem; rather, the teeth strip too easily. I have attempted to 3d-print these gears out of nylon, hoping they would hold up better, but have not been successful in keeping the nylon print from warping. (One of these days I'll make an enclosure and try again ....) I also have some POM filament (trade name Delrin), but it warps even more than the nylon, so again, waiting on an enclosure.

Obviously there is success to be had in some applications, since many 3d extruders use printed gears. It may be that have succeeded even with gears undergoing a greater stress than in an extruder, and if so, I will be very eager to hear about it - I'd like to know how to achieve success!
Sounds like my best bet is to just stick with the brass and make another if it wears out. Obviously this is not a precision piece. If I start replacing too many parts on this saw it is just going to be cheaper to replace it. I am finding that the roller guides are also pretty worn and they also are not available. I saw the same saw on craigslist or facebook a while back for $40 and thought that is just like mine. I should have bought it but that was before the tire came off on mine. Now I have $30 in new tires and I am having trouble keeping the blade on it.
 

popnrattle

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I drew a bevel ring and pinion(4.11 to 1 ratio) along with the spiders and printed them as part of an auto differential display to show students how it works. I uploaded my 2 procedures using CAD and Inventor(correct or not;)) to you tube if you care to take the time. The musical accompaniment may not appeal to you so just mute it.
 

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