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Makers and Making: Looking for Bevel gears or equivalent
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Oct 26th 2009
I've been working out some plans for a prototype version of the electricity free table saw for the past couple of weeks. I work with small wood parts frequently and would love one, but can't justify the price tag. That it was posted on the Make blog means I should reach out and ask for some help:
http://blog.makezine.com/archive/2009/10/electricity-free_tables_aw.html
The aspect I'm having the most trouble with is the blade raising mech. I think bevel gears (much like theirs) would be the way to go, but I know admittedly little about specs for gears. I'm having trouble finding affordable gears to try out in a prototype.
I briefly considered a worm gear setup (I have one from an old garage door opener), but felt that it would be far too slow. After watching the vid a couple dozen times, I came upon the conclusion that you want about a 1:1 ratio (or very close to it) for cranking the threaded rod. Since you're turning a rod that raises and lowers the saw itself, you're already getting quite a bit of control over the height. Going any finer and it would really slow the process down.
I've looked into several sets of differential bevel gears used in RC cars, but I think they're likely too small (the shaft diameter typically maxes out at 1/8"). While I suppose I could have an 1/8" shaft drive a 1/4" threaded rod for the lift, I think it'd be better to work at 1/4" all the way through.
I saw a die cast set of gears on my stove top popcorn maker (<$20) so there must be a source for these that's affordable to play with. Unfortunately, I JUST threw out an old mixer that probably had some gears in it.... It figures.
I'm also considering using a wooden gear box similar to this:
http://woodgears.ca/router_lift/index.html
The downside is that it's much bulkier than an all metal solution and would likely hamper the tilt mechanism or at least make the whole structure far larger than I'd like. The upside is that it'd be fairly inexpensive prototype for the basic table. It'd probably be better adding the tilt after I figure out if it can be made by me at all anyway.
In case anyone was wondering, I was going to use the stop motion dolly plans as a base for the sliding table parts:
http://www.stopmotionworks.com/articles/stopmocamdolly.htm
I had been debating whether to just slide the pieces across the work surface, or do a sliding table. I think I'm going to try for the sliding table. Again, working with very small pieces is one of the primary reasons for trying this out, I think the sliding table may be the way to go, but may also be the first "feature" to be dropped.
Well, if anyone has some nifty suggestions for changing horizontal rotary crank motion in to vertical rotarty motion, I would love to hear it. Even better would be a good source for affordable bevel gears (I'm looking at $10 per set if that's even possible).
http://blog.makezine.com/archive/2009/10/electricity-free_tables_aw.html
The aspect I'm having the most trouble with is the blade raising mech. I think bevel gears (much like theirs) would be the way to go, but I know admittedly little about specs for gears. I'm having trouble finding affordable gears to try out in a prototype.
I briefly considered a worm gear setup (I have one from an old garage door opener), but felt that it would be far too slow. After watching the vid a couple dozen times, I came upon the conclusion that you want about a 1:1 ratio (or very close to it) for cranking the threaded rod. Since you're turning a rod that raises and lowers the saw itself, you're already getting quite a bit of control over the height. Going any finer and it would really slow the process down.
I've looked into several sets of differential bevel gears used in RC cars, but I think they're likely too small (the shaft diameter typically maxes out at 1/8"). While I suppose I could have an 1/8" shaft drive a 1/4" threaded rod for the lift, I think it'd be better to work at 1/4" all the way through.
I saw a die cast set of gears on my stove top popcorn maker (<$20) so there must be a source for these that's affordable to play with. Unfortunately, I JUST threw out an old mixer that probably had some gears in it.... It figures.
I'm also considering using a wooden gear box similar to this:
http://woodgears.ca/router_lift/index.html
The downside is that it's much bulkier than an all metal solution and would likely hamper the tilt mechanism or at least make the whole structure far larger than I'd like. The upside is that it'd be fairly inexpensive prototype for the basic table. It'd probably be better adding the tilt after I figure out if it can be made by me at all anyway.
In case anyone was wondering, I was going to use the stop motion dolly plans as a base for the sliding table parts:
http://www.stopmotionworks.com/articles/stopmocamdolly.htm
I had been debating whether to just slide the pieces across the work surface, or do a sliding table. I think I'm going to try for the sliding table. Again, working with very small pieces is one of the primary reasons for trying this out, I think the sliding table may be the way to go, but may also be the first "feature" to be dropped.
Well, if anyone has some nifty suggestions for changing horizontal rotary crank motion in to vertical rotarty motion, I would love to hear it. Even better would be a good source for affordable bevel gears (I'm looking at $10 per set if that's even possible).
Oct 26th 2009
I SEEN that saw for $1200. Too pricey .
Try these online stores they might have gears you can use.
LET us know how your project turns out! Post some photo's.
https://sdp-si.com/eStore/PartDetail.asp?Opener=Group&PartID=32193&GroupID=613
https://sdp-si.com/eStore/Direct.asp?GroupID=203
I hope this helps.
Try these online stores they might have gears you can use.
LET us know how your project turns out! Post some photo's.
https://sdp-si.com/eStore/PartDetail.asp?Opener=Group&PartID=32193&GroupID=613
https://sdp-si.com/eStore/Direct.asp?GroupID=203
I hope this helps.
Oct 27th 2009 edited
http://www.mcmaster.com/#bevel-gears/=48q6vv << here at the bottom of the page, gears start around $2 to $3 each, less than $10 a set!!
They also carry threaded rod, go for some 3/8-16 (approx 16 turns per inch this would be great for raising the blade a 1/16th of an inch at a time.) threaded rod or if you are building a lighter weight version go for some 1/4-20 rod.
If that is still too fine, check out their ACME rod and nuts ( http://www.mcmaster.com/#acme-screws/=48q9to) , these are used in motion applications such as CNC drives and such, but still low cost and affordable.
My .02
They also carry threaded rod, go for some 3/8-16 (approx 16 turns per inch this would be great for raising the blade a 1/16th of an inch at a time.) threaded rod or if you are building a lighter weight version go for some 1/4-20 rod.
If that is still too fine, check out their ACME rod and nuts ( http://www.mcmaster.com/#acme-screws/=48q9to) , these are used in motion applications such as CNC drives and such, but still low cost and affordable.
My .02
Oct 27th 2009
If you pull this off, you really should make the plans available for us! This is exactly the type of thing I've been looking for to put together an all-unpowered workshop. There are some things that will be unavoidable, but this would be a huge help. Best of luck with this.
Oct 27th 2009
Thanks for everyone's help. Those are some great resources.
I will definitely be documenting this and getting back to you all (assuming I actually find the time to do it). I'll even do my best to document a failure. It just might give someone else the right kick to do a working version!
I will definitely be documenting this and getting back to you all (assuming I actually find the time to do it). I'll even do my best to document a failure. It just might give someone else the right kick to do a working version!
Oct 28th 2009
I am also interested in making one of these, it would come in very handy with some of the stuff I do..... I can fabricate all the metal parts here in my shop, I have access to a CNC plasma cutter (and a ton of other metal working tools) that I can use to cut all the metal end plates, and I might use some ball bearing drawer slides for the top guide plate.......
4 days ago edited
Just wondering if you've made any progress with this. Since reading about the saw, I've come up with an almost complete, but completely terrible design. It's only hand-drawn at the moment, so unfortunately I can't yet share.
I have incorporated ACME Screws and nuts in the design for lifting the blade, and a large wooden dowel and steel tubing to allow for miter adjustment. It's not great, but when I have the money I may make a try at it.
As far as the sliding table goes, I've been considering using two square channels of different sizes with skateboard bearings suspended on bolts. I'm not sure if that's very clear, but I'll draw it up and share.
I had a bit of an idea about the hand crank. Would it be possible to use a chain drive from a bicycle down to a foot (like bass drum) pedal? That way, when you press your foot down, it would raise the blade, but wouldn't lower it when you lift your foot. You'd have to hand-crank it back down, but I don't think that would be too unreasonable.
*Edit
http://imgur.com/yoPKf
Here's a drawing of the table system. The block in the lower channel would be a piece of MDF the length of the slide that has raceways routed in it to allow the bearings to roll freely while not going from side to side.
It now dawns on me that I have re-invented bottom-mount drawer slides.
I have incorporated ACME Screws and nuts in the design for lifting the blade, and a large wooden dowel and steel tubing to allow for miter adjustment. It's not great, but when I have the money I may make a try at it.
As far as the sliding table goes, I've been considering using two square channels of different sizes with skateboard bearings suspended on bolts. I'm not sure if that's very clear, but I'll draw it up and share.
I had a bit of an idea about the hand crank. Would it be possible to use a chain drive from a bicycle down to a foot (like bass drum) pedal? That way, when you press your foot down, it would raise the blade, but wouldn't lower it when you lift your foot. You'd have to hand-crank it back down, but I don't think that would be too unreasonable.
*Edit
http://imgur.com/yoPKf
Here's a drawing of the table system. The block in the lower channel would be a piece of MDF the length of the slide that has raceways routed in it to allow the bearings to roll freely while not going from side to side.
It now dawns on me that I have re-invented bottom-mount drawer slides.
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