# "The Simplest Frame Jig"



## BentChainring (Jul 10, 2008)

At least the simplest frame jig this guy could come up with. This may have been posted before, sorry I am kinda new to this forum (but frequent RBR). I did a cursory search for this jig in this forum, and didnt find anything.

Thoughts? I would think the weakness is in getting any movement in the joints during fabrication. Some kind of dowel pins at the corners to keep it true seems like it may help with that issue. The adjustments are a tad cloogy, meaning there will be some tapping and adjusting to get everything right, but seems doable. And since there are no scales for distances, a good set of 0-24 or 36" calipers may be in order to get distances as close as possible.

http://www.instructables.com/id/The-simplest-bicycle-framebuilding-jig-I-could-com/


----------



## unterhausen (Sep 28, 2008)

looks...familiar

Don't fabricate in a jig like that, tack or pin and braze/weld outside the jig.

The simplest jig is no jig. I have built bikes with a 4' straightedge and a fixture which aligns the bb to the seat tube, which is more than a lot of people use.


----------



## MaxxCutts8 (Nov 7, 2008)

Has any one used a jig like this? I really haven't ever seen it before


----------



## unterhausen (Sep 28, 2008)

my thought is that aligning it would be a chore. I don't know if I would say it is simple. There are people that use a "picture frame" style jig made out of structural steel. This one is similar to that.


----------



## zipzit (Aug 3, 2005)

I thought the simpliest jig was the one described on http://http://www.instructables.com/id/Almost-jigless-bicycle-frame-building/ .. (referenced in the margin of the your link...)

See also
http://forums.mtbr.com/showthread.php?t=380315 Shiggy has provided some nice photos.

I'm thinking of using the jigless fixure myself for my first time build, with verifications using full size CAD printouts and the top of my shop table saw, an industrial Jet 3HP. (along the lines of WWTO build with what jay_ntwr is doing) Tools I have are: lots of feeler gauges, dial indicator. I'm figuring that I will have to buy a nice digital angle gauge to .2 deg resolution, and some V shaped tube holding blocks. What I haven't figured out is how to build a bottom bracket holding fixture that will sit on my saw to hold the weight of the frame rock solid, and in perfect square (Coconino style...)



unterhausen said:


> ...The simplest jig is no jig. I have built bikes with a 4' straightedge and a fixture which aligns the bb...


Unter, What I don't understand is how do you use a 4' straightedge? What do you do with that, particularly with different size tubing ?

Ooooh.. wait.. I can see how you might hold a 4 ft straight edge on the ends of the bottom bracket, then use feeler gauges to verify that the Seat Tube is perpendicular to the BB, and do this again on down tube... but that's only part of the big picture. How can you verify that the head tube is aligned correctly only using simple tools and a 4 ft straight edge? I'm not seeing it.

Don't mean to be offensive here, just trying to pick up hints to help a virgin build as appropriate. Many thanks, zip..


----------



## coconinocycles (Sep 23, 2006)

zipzit said:


> What I haven't figured out is how to build a bottom bracket holding fixture that will sit on my saw to hold the weight of the frame rock solid, and in perfect square (Coconino style...)


hey, man - you *could* buy a BB tower brom Joe Bringheli and drill a hole in your table for it.........you have plenty of measurement gauges.............a height vernier & a good square and a park *** tool & you are good to go! Steve Garro, Coconino Cycles.


----------



## Cracked Headtube (Apr 16, 2006)

*** = F.A.G. or Frame Alignment Gauge
without the periods the forum editor thinks its a naughty word....


----------



## coconinocycles (Sep 23, 2006)

unterhausen said:


> my thought is that aligning it would be a chore. I don't know if I would say it is simple. There are people that use a "picture frame" style jig made out of structural steel. This one is similar to that.


my 1st 30-ish frames were on a 70's era Stein jig & you had to measure ALLOT of variables, the BB was the only fixed point. get yer highschool geometry down, esp. in regard to how triangles interact........Steve.


----------



## dr.welby (Jan 6, 2004)

BentChainring said:


> Thoughts? I would think the weakness is in getting any movement in the joints during fabrication. Some kind of dowel pins at the corners to keep it true seems like it may help with that issue. The adjustments are a tad cloogy, meaning there will be some tapping and adjusting to get everything right, but seems doable. And since there are no scales for distances, a good set of 0-24 or 36" calipers may be in order to get distances as close as possible.


Well, that's mine, as is the even simpler one that was also mentioned upthread.

And as the title says, it the simplest I could come up with that was a complete standalone jig and wasn't a complete pain in the butt to set up. However, this means there are plenty of places you can make improvements to tighten it up or make setup faster, give you have the time, money, machine tools, etc. It would just become "A slightly more complicated and expensive jig that I came up with"....

The reason I took the time to post it up to Instructables was so that someone(s) smarter than I could see the whole process and then figure out ways to do things better. Or cheaper, which is better in my book.

As for dowel pins in the corners, I'm not sure which corners you are referring to. The corners of the picture frame? I do mention that one could put "gibs" of material that ride in the extrusion slots to keep the cone assemblies aligned, and that you could make tubular sleeves to shim up the bolts at the end of the two main adjustable beams. I keep saying I'm going to add them to mine, but I never get around to it.

As for the adjustments, I'm not sure what jigs you have used that don't need a tap here or there. Its not a big deal, my mallet was cheap and I don't have to pay for it by the tap (don't tell the cell phone companies!)

There is a scale for setting the bottom bracket drop, and I added one for the head tube height. You could add another along the base of the picture jig but I've found that with my workflow a metal meterstick works just fine.

If you want precision and easy set-up, buy an Anvil. But for us garage builders who build a frame or two a year, a simple jig is generally not the limiting factor in our speed or precision. And the money saved can be used to buy extra tubes to replace the ones where we cut the miter in the wrong direction (guilty), kinked chainstays (very guilty), and water bottle bosses on the wrong side (yup, did that too, and btw I think liberal use of Sharpie pen has had more a positive impact on my frames than upgrading my jig!).

But anyway, I'm here, if you have questions, comments, ideas, or whatever just post 'em up.


----------



## zipzit (Aug 3, 2005)

Doc / Steve G. / (& walt, shiggy, Dave B,...) many thanks to you guys for sharing your craft with us wannabees. I only hope some of us can repay the favor.



dr.welby said:


> ...to replace the ones where we [put the] water bottle bosses on the wrong side (yup, did that too, ...)


I saw a cool fix for that problem the other day, as long as you are making a single speed bike frame.. Felt Beernut 15mm socket / bottle opener combo tool...








(quote from the sales staff @ cambria bike...Perhaps the world's coolest wrench, the Felt BEERNUTS tool is one spanner no tool collection - or bike - would be complete without. This little guy has a 15mm hardened steel box wrench on one end and a bottle opener on the other. Drilled so it will bolt on to standard H2O boss holes and includes handy wing nut-style boss inserts. Use the inserts or just bolt it to your bike with existing H2O bolts - either way. Made of 4130 Cromoly with a stain finish and laser etched Felt logo. What are you waiting for?

zip..


----------



## BentChainring (Jul 10, 2008)

dr.welby said:


> But anyway, I'm here, if you have questions, comments, ideas, or whatever just post 'em up.


Wow! There you are!

I am really getting psyched about this project (building the jig). I have been looking for something relatively simple (and cheap), so I can put a few frames together.

I dont mind tapping and adjusting, I am used to putting machine setups together, so tapping and fitting isnt a problem. I think to get the "picture frame" square I am going to take a trip with the 80/20 to a friends machine shop and after rough cutting the material, facing it square (rather than using dowel pins).

I am also putting CAD models together (mainly because I am out of practice with solidworks), and have started with your fork jig. I really like the fork jig because its so simple, and can achieve various offsets with ease. One suggestion would be to turn the gusset plate around, so you can build zero offset forks.

Thanks again, and youll be seeing me around!


----------



## dr.welby (Jan 6, 2004)

BentChainring said:


> One suggestion would be to turn the gusset plate around, so you can build zero offset forks.


Huh, that's a really good idea! Never occurred to me, though I don't build zero offset forks.

Would you mind signing up at Instructables and leaving it as a comment? Then others can see it.

If you build the fork jig, I recommend adding another piece of 3030 under the V-block to space it up. I think I mention that in the Instructable, but it's a worthwhile upgrade.


----------



## BentChainring (Jul 10, 2008)

dr.welby said:


> Huh, that's a really good idea! Never occurred to me, though I don't build zero offset forks.
> 
> Would you mind signing up at Instructables and leaving it as a comment? Then others can see it.
> 
> If you build the fork jig, I recommend adding another piece of 3030 under the V-block to space it up. I think I mention that in the Instructable, but it's a worthwhile upgrade.


Got it, excellent Idea.

I am going to probably end up taking this jig back to my university (Cal Poly, SLO), since they teach a bicycle design class, and I AM POSITIVE, would be interested in an upright frame jig.

The fork jig is important for building forks, and sometimes we even use negative offset forks to get the handling characteristics right for recumbent bikes. A former professor at the university wrote a book on bicycle handling and provides equations which seem to match reality much better than those provided in Bicycling Science. They have built recumbents that non-cyclists ride with ease.


----------



## dr.welby (Jan 6, 2004)

BentChainring said:


> I am going to probably end up taking this jig back to my university (Cal Poly, SLO), since they teach a bicycle design class, and I AM POSITIVE, would be interested in an upright frame jig.


You should see the scars I have from sliding out a HPV in the UC Davis parking lot at the ASME HPV Championships around '94 or '95.


----------



## BentChainring (Jul 10, 2008)

dr.welby said:


> You should see the scars I have from sliding out a HPV in the UC Davis parking lot at the ASME HPV Championships around '94 or '95.


We used lots of Kevlar, and encouraged the newbies to slide out some of the old bikes to know what it feels like.

My buddy and I built a bike to try for the human powered speed record out at Battle Mtn. Nevada in 2006... man that was fun!

I am trying to get into frame-building as a hobby, and maybe something more one day in the future. I did alot of work with the Mini Baja and Formula teams at CPSU... and after leaving school for Big Aerospace, I need to find a creative outlet.

I think the first bike will be a bamboo frame.... funny... since I have had my Miller Dynasty 200DX sitting mostly idle since I graduated...


----------



## dr.welby (Jan 6, 2004)

BentChainring said:


> We used lots of Kevlar, and encouraged the newbies to slide out some of the old bikes to know what it feels like.


We were running unfaired in that road race because the corners were so tight. Hence the scars.


----------



## BentChainring (Jul 10, 2008)

dr.welby said:


> We were running unfaired in that road race because the corners were so tight. Hence the scars.


Ouch...


----------



## BentChainring (Jul 10, 2008)

Fork Jig drawn up... 

I went with a 30" vertical tube to give myself plenty of room. Flipped the gusset plates around, and added a spacer place behind the V-Block.

I also discovered that the 80-20 Living Nub is 2.937" wide... and Front Fork Spacing is 3.937". I will probably just machine the dropout clamps and screw them into the Nub.


----------



## unterhausen (Sep 28, 2008)

zipzit said:


> Unter, What I don't understand is how do you use a 4' straightedge? What do you do with that, particularly with different size tubing ?
> 
> Ooooh.. wait.. I can see how you might hold a 4 ft straight edge on the ends of the bottom bracket, then use feeler gauges to verify that the Seat Tube is perpendicular to the BB, and do this again on down tube... but that's only part of the big picture. How can you verify that the head tube is aligned correctly only using simple tools and a 4 ft straight edge? I'm not seeing it.
> 
> Don't mean to be offensive here, just trying to pick up hints to help a virgin build as appropriate. Many thanks, zip..


I don't really want to hijack this thread with a discussion of jigless building. The thing about jigs is that you can end up with a frame badly out of alignment. I just did it screwing around practicing my brazing, so no big deal, but still something to keep in mind. Here is a discussion about how to build jigless from the framebuilders list: jigless build The sketchy part from most people's perspective is using your eye to align the HT with the ST.


----------



## Typo_Knig (Aug 8, 2009)

Nice Solidworks model, you know you can download practically every part made by 80/20 at 3D Content Central in pretty much any file format known in the CAD world.

http://www.3dcontentcentral.com/parts/supplier/80 20-Inc.aspx


----------



## quietcornerrider (Jun 6, 2009)

Well, I thought I'd add my model I just mocked in sketchup. I like to see exactly what's what before I order parts, so I thought this was a good idea. 

I need advice before I build it, so any thoughts/corrections are welcomed.

1st pic: overall jig
2nd pic: Angle Gauge x2
3rd pic: bottom bracket holder
4th pic: Dropout holder (Old fake hub from my pickup truck days)
5th pic: headtube holder
6th pic: seattube holder

What do you think I should make the cones out of? Rock maple springs to mind, but then again, I have an acquaintance that works in a machine shop.

Thanks folks!

*edit* Wow, resizing did a number on the pic quality. Sorry.
*edit#2* Ah. I found a way to remove the images!


----------



## quietcornerrider (Jun 6, 2009)

*Lemme try this again.*

I wish they didn't take up so much space.
Lets hope these work, if they don't, I'm giving up.
(Ah, good. Much better!)


----------



## dr.welby (Jan 6, 2004)

quietcornerrider said:


> Well, I thought I'd add my model I just mocked in sketchup. I like to see exactly what's what before I order parts, so I thought this was a good idea.
> 
> I need advice before I build it, so any thoughts/corrections are welcomed.
> 
> ...


I think you need a different strategy for the rear axle holder, since the pickup truck mounts are spaced for front hubs. Unless you plan to bore it out and install a rear axle, but the question is can you do that accurately?

The four bolt clamping the top beam aren't going to line up unless you run single t-nuts and slot the beam. It's easier just to slot the angle gauge once. You could slot the beam in one of the channels, but you only need one bolt to hold it down. However, it will limit the vertical range of the tube holder on the beam.

For cones, you may be able to improvise with trailer ball hitches, clutch alignment tool cones, or certain shower heads.


----------



## quietcornerrider (Jun 6, 2009)

dr.welby said:


> I think you need a different strategy for the rear axle holder, since the pickup truck mounts are spaced for front hubs. Unless you plan to bore it out and install a rear axle, but the question is can you do that accurately?
> 
> The four bolt clamping the top beam aren't going to line up unless you run single t-nuts and slot the beam. It's easier just to slot the angle gauge once. You could slot the beam in one of the channels, but you only need one bolt to hold it down. However, it will limit the vertical range of the tube holder on the beam.
> 
> For cones, you may be able to improvise with trailer ball hitches, clutch alignment tool cones, or certain shower heads.


Ah. Much appreciated. The rear axle holder is technically wide enough for a rear hub. Actually, it's obnoxiously long. So I don't think it will be a problem, but since this is the testing phase, I'll find out with time.

I was in a hurry to finish the mock up, so I forgot about the slot in the angle gauge. Thank you very much for reminding me. I'll have to put that in so I don't forget again.

Ball hitches I hadn't thought of, but I like the shower head idea. Cheap too.

Thanks for the input.


----------



## dr.welby (Jan 6, 2004)

quietcornerrider said:


> Ah. Much appreciated. The rear axle holder is technically wide enough for a rear hub. Actually, it's obnoxiously long. So I don't think it will be a problem, but since this is the testing phase, I'll find out with time.


Also double-check the axle size - front axles are 9mm and rear are 10mm.

Your BB mount is currently above where the beam will pivot where it's clamped to frame, so it will shift as you adjust the seat angle. You can fine-tune your way around this, but if it's concentric with the pivot it makes set-up a little easier.


----------



## quietcornerrider (Jun 6, 2009)

Again, thanks!


----------



## zipzit (Aug 3, 2005)

Here's a question. On a tight budget, how do you make sure all the key mounting points are on a single plane? That would be difficult to do without a large layout plate and measuring tools... Expensive. I've been toying with using fishing line and gravity to measure flat plane, but its just not that easy.

I'm thinking... would it be possible to pick up an extra bottom bracket, then attach a cheap keychain type red laser pointer to it, centered up? You could then spin the bb/laser thing 360 about its mount, verify everybody is on plane? You could put this together for less than $20.. little bit of scrap steel, some finely threaded rod, a cheap laser. You'd have to wire the laser to the all-thread (I was thinking a fine tie wire with spring to maintain tension.. something that would allow for slight alignment movement yet maintain stability from bench to jig. If the wire isn't stable enough, you could spot weld two nuts to the bottom of a short piece of small angle iron, then nest the laser in the V of the angle iron. I think that would work.)

Calibrate the BB-laser on a small flat plate (top of table saw?) measure height of beam 2" from BB, then measure it again as far away as possible. Make sure beam is exactly 1/2 BB width, and perpendicular (oops.. parallel) to end of BB tube. Use the nuts on the all-thread for fine adjustment. I'm just thinking out loud here.. You would have to figure a way to ensure ends of ST & HT cones have visible center on then. Also mark center on rear axle / dropout holder.

Something like this? 









Comments?

zip...


----------



## dr.welby (Jan 6, 2004)

zipzit said:


> Here's a question. On a tight budget, how do you make sure all the key mounting points are on a single plane?


If you're on a tight budget, you deal with the tolerance of the 8020 and just measure off of the beam. 

But the laser thing is rad and I hope somebody makes one! I might have to...

What about renting a laser level for a weekend? Set your jig on a workbench with the laser's plane a few inches above it and measuring down with a ruler shim it until the jig's frame is level. Then measure down to all of your hard points at their respective outside diameters or other reference points.


----------



## quietcornerrider (Jun 6, 2009)

I LOVE the laser idea. I mocked up this:

So, You can move it up and down the entire length of the left post, and even turn it to hit the BB holder and rear axle. You'd just have to mark the center of the BB shell, the head tube and seat tube. And it would cost all of $4 for angle bracket, .99 for the laser from the checkout line at walmart and .29 for the allen bolt.

Actually, looking at it again (I have the almighty power of ZOOM!), I see, it wouldn't have to move up and down, just have to rotate. You could hit everything one at a time, arcing from highest point to lowest.


----------



## toddre (Mar 1, 2004)

A bit late to the game here, and i really knoww nothing, but how about using a properly spaced 1-2-3 block for a real axle.?


----------



## quietcornerrider (Jun 6, 2009)

What exactly is a 1-2-3 block?


----------



## rustola (Jan 15, 2008)

quietcornerrider said:


> What exactly is a 1-2-3 block?


http://lmgtfy.com/?q=1-2-3+block


----------



## quietcornerrider (Jun 6, 2009)

rustola said:


> http://lmgtfy.com/?q=1-2-3+block


Ah. Is this the smartass' way of saying google it yourself?


----------



## MrCookie (Apr 24, 2005)

*Simple Jig*

Hard to say how many frames came out of this jig, over a hundred. It is pretty stinking simple.


----------



## zipzit (Aug 3, 2005)

MrCookie said:


> Hard to say how many frames came out of this jig, over a hundred. It is pretty stinking simple.


Simple, yes, but the devil is in the details. 
--I'm assuming you make the front triangle for the tandem on a traditional bike frame jig, them move it over here to your tandem jig?
--At the top of the jig, how do you ensure the seat tubes / down tube is centered in the slot? Shims? Wedges? How much slop is in there? 
--How do you get the frame out of the jig? Is it bolted somewhere? Its not clear from your photos.

--zip


----------



## MrCookie (Apr 24, 2005)

It's not my jig, I had the opportunity to ride one of the builder's LWB recumbent bikes 10 years ago, and managed to find his archive on the web.
I am not sure how it comes apart, but it looks to me like with a little wiggling, you could lift it up and forward enough to get the rear end past that vertical tube, and then drop it out the side?


----------

