How to? tacking jig fot TIG welding frames

Who can point me in the right direction????

I have looked at the commercially available jigs and WOW! they are costly, besides the initial cost I would fear the price to ship over to Africa.

So that brings me to DIY. I am looking for a good solid design or plans to build my own. I see 8020 seems to be the weapon of choice for most DIY jigs. So looking for good design using 8020. I have a machine shop so milling and turning pieces not a problem. Would rather like a good solid design over something that is just bolted together with hardware nuts and bolts.

Any help would be greatly appreciated.

This thread has some great pics for ideas if you can think about tacking horizontal rather than vertical and with a machine shop very doable.

http://www.velocipedesalon.com/forum...ild-30714.html

There're many different diy ways, from just tube blocks over a flat surface, to the commonly used 8020 based ones.

I would recommend having your own thought first on how do you feel confortable or how is your building procedure, as this will define how your jig would be. What is ok for someone, might not suit you (for example you might tack differently to others, build different type of frames (fat bikes, recumbents, etc) or any other question.

Having a Jig is one of the big investments, as welding equipment, etc, so better to be 100% sure the actual jig will be something you're happy with and not something you'll end up changing after 20 frames, or wishing something might have been done differently.

Anyway, this is not whay you asked for, I guess... just in case is of any help for you, here is the original drawins I made for my own jig, althoug you should take it just as a sample or reference, not as an absolute or the like. One of the main things of the jig is that I can change BB or dummy axles so to accomodate different type of bb and dropout widths. Your main target should be keep HT/BB/DPT in very same axle and warranty enough access to all areas so to be able to reach with the torch (mine can rotate, for example). All you need is to think a little bit measures so to make sure it will all stay in the same axle.
Jig Drawings (pdf)

Anyway, there're loads of posts and info in this forum about this very same question, and many other places (flickr has some cool pictures around) so you should be able to figure your own design.

Cheers

I'll suggest a flat surface before a jig. With some creativity it will act as a jig then also be used to align the tacked construct before the finish welding. The flat surface has more uses besides bike frames, making it more likely to be found used and then sold after your building phase is done with. A 2'x3' is the smallest that is easy to build with and is not too big or heavy yet. I would save your jig construction for the tube holding on the surface devices and the other fixturing needs like braze one and alignment tooling. After you build a frame or three what needs a jig should have will be far better understood. Andy.

Check out 44bikes Flickr page. Kris Henry has one of the best 8020 based frame jigs I've seen.

There's a link to a wordpress site that I created in my sig that has a bunch of homebuilt jigs...many of them are 8020. Not all of us have the cheddar or the space for a dedicated plate.

Here is the link to my frame jig set for those interested: 44 Bikes : Frame Jig

Kris (44 Bikes) shared a bit of info the parts he machined for his jig and this is what I came up with knocking off the basic design and adjustability of the Anvil jig . I had access to a lathe and good machine drill press to make the parts. I bought most of the material and re-purposed some that I had already. Everything adjusts independently of other points - top tube length, head tube angle, seat tube angle, bottom bracket height and chainstay distance. The right angle brackets keep it scare and the plates on the back keep the three main 80/20 pieces in plane. Total cost was about $600 and a month of my spare time.

http://farm9.staticflickr.com/8256/8...bf443381_c.jpg

http://farm9.staticflickr.com/8131/8...9826c698_c.jpg

http://farm9.staticflickr.com/8275/8...9b301422_c.jpg

http://farm9.staticflickr.com/8559/8...8e3c108d_c.jpg

http://farm9.staticflickr.com/8547/8...97f50d7c_c.jpg

I've built 3 frames using TIG. For the main tube-tube joints I use a flat peice of metal with V-blocks on their sides bolted to it. I use a digital angle finder to check the angle. It's rather tricky and time consuming to set up but it works. The worst frame of the 3 has 0.5 deg HT twist, as far as I can measure with the angle finder.

My "peice of flat metal" is 1"x 1" angle iron, 1/8" thick.

For the rear end I used the same 1" angle iron with a hole drilled for a dummy axle. I bolted the BB to a piece of 8mm plate which was bolted to the angle iron, otherwise the stays hit the angle iron.

My method is a lot like the "almost jigless" instructable project. I honestly didn't think it would be good enough, so I did a lot of test pieces using cheap mild steel rolled and welded tube. Welding sequence is definitely the most important thing for getting a straight joint, with tight, tight mitres coming a close second.

It could have been a lot faster and easier if I'd bought a jig. I didn't have the budget to buy one and didn't have the inclination and skills to build one. If I decide to build commercial quantities of frames I'll deffo get a jig but until then it's angle iron and a digital angle finder for me :)

I must say that you guys have done spectacular jobs of building your own jigs, I hope when I get onto building mine it is going to be close to as good as Kris and Todd's jigs.

I am interested to know what is the specific profiles (dimensions) of the 8020 that Kris (44 Bikes) used for his jig. I I like the idea of having the very large section as the backbone.

The pictures have helped me understand what I need to do as far as machine work goes.

Very grateful for everyone's advise, thank you.

Glad to see you guys working through the process of designing and building your own fixtures...you learn so much more about bicycle design during the fabrication of your fixture than you ever will writing a check and purchasing one.

Well done all,

rody

Quote:

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Originally Posted by darthmuller

I am interested to know what is the specific profiles (dimensions) of the 8020 that Kris (44 Bikes) used for his jig.

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All 8020 parts that I have used are the Metric 40 Series. The beam profile part no's I've used are:

40-8016 (80mm x 160mm)
40-8080 (80mm x 80mm)
40-4080 (40mm x 80mm)

Basically all the heavy wall metric profiles.

Quote:

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Originally Posted by Rody

Glad to see you guys working through the process of designing and building your own fixtures...you learn so much more about bicycle design during the fabrication of your fixture than you ever will writing a check and purchasing one.

Well done all,

rody

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That's true!
I learned a lot when designing parts for my jig which is based to 44 Bikes Kris's jig. Thanks Kris for the help!

Dummy axle holder still need to be done, but I'm not sure how it will be done yet.

http://i1237.photobucket.com/albums/...ps7a1006c3.jpg

Quote:

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Originally Posted by fortyfour

All 8020 parts that I have used are the Metric 40 Series. The beam profile part no's I've used are:

40-8016 (80mm x 160mm)
40-8080 (80mm x 80mm)
40-4080 (40mm x 80mm)

Basically all the heavy wall metric profiles.

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Kris

Thank you for sharing the information on the size profiles you have used, big help. Now I just need to hunt for them here in Africa.
Question: do you complete all the welds in your jig? Or are some of them done on a flat weld table?

Quote:

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Originally Posted by dsaul

Check out 44bikes Flickr page. Kris Henry has one of the best 8020 based frame jigs I've seen.

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RISD! That is correct, right Kris?

Hi there

many thanks for this great discussion

i like this 8020 Design - it looks pretty impressive and very well done.

https://www.flickr.com/photos/44bike...5727223/page2/