Homemade old school chain tensioner

[us56456712]

Find a 2 and a quarter inch carriage bolt that fits your slide out threads. Two inch might also work. Mine was 1/4 by 20 TPI. Screw it in all the way to make sure it's good. If you use a used carriage bolt and it is slightly bent it won't thread into the slide outs on the bike.

Put the bolt head in a vice so that you can follow the square on the carriage bolt head with your hack saw. Saw off one side, the opposite side and then the last two sides. File smooth.

Put the part you made square in a drill press. Turn on the drill press to make sure it doesn't wobble. They never wobble in my press but I always check. Put on nuts and tighten them finger tight until just enough for the thin end you want to make protrudes past the nuts. You can use washers between the nuts if you need to fine tune it.

Turn on the drill press and use a file to go back and forth, using the bottom nut as a guide to hold the file against. This prevents the file from jumping around and lousing up your threads. The nuts get tighter if you hold the file on the right side. You will need to use a wrench and vice to remove the nuts as they become locked a little tight. Removing the nuts straightens out the threads where you filed them off.

Finished product.

3/16 open end wrench fits. It's a little loose but works.

Finished, quick and inexpensive.

 

[LukeTheJoker]

Nice work!

 

[OneHorsePower]

i tried making some for my elgin last time and the ends kept bending cause it was cheap hardware store bolt steel ,
but i ended up using a big washer on both sides of the drop out on the axle , and the original bolts with the broken pins pushed on both washers instead of reaching the axle

 

[us56456712]

i tried making some for my elgin last time and the ends kept bending cause it was cheap hardware store bolt steel ,
but i ended up using a big washer on both sides of the drop out on the axle , and the original bolts with the broken pins pushed on both washers instead of reaching the axle

They do bend, especially on a Klunker. Try grade 5 carriage bolts or heat and rapidly cool the thin ends. If cooled too fast they become brittle and snap off. Sometimes they work and sometimes they bend. So far the only problems I have had with them bending is on Klunkers. In the old days we used thumb screws. We didn't turn the ends down but filed the washer on the axle flat on one side, making sort of a "D". The thumb bolt tip was positioned against the flat part of the axle washer. We did this in the 50s when we were kids. We did a lot of funny stuff to these old bikes. We took a Schwinn seat post and put it over the 5/8 rod post, drilled a hole through the modern post and the solid post and bolted them together. That way a more modern seat would fit. Most of the time it ended out coming loose and rocking. Once we hooked two bikes together, filing the fork to fit on the rear axle and making sort of a 3 wheeled tandem. We thought that was real funny and still talk about it.

 

[murdercycles]

awesome idea. well done

 

[xray]

excellent

 

[us56456712]

You can also use thumb bolts without tapering the threaded end. Just screw it into the drop threads and have it push on an axle washer that has one dude ground flat, like a D. The bolt pushes on the washer flat. We used to do that when we were kids.