Sunday, February 16, 2014

It Only Fits One Way

I’ve made a lot of jigs to make projects go quicker and produce reliably similar items.  For items which sell well I usually make several of them at one time then store the tools, jigs, templates, blanks, whatever, away until needed again.  Sometimes it is quite a few months between these production runs and I tend to forget how all the parts worked.  Some jigs are a bit complicated.  With each use I try to improve the written and photo image instructions but it’s hard to record every little detail.

In designing jigs I try to design constraints which only let the workpiece fit one way. This seems the surest way to make tooling that can’t get messed up.

This is one example.  On my shop built version of a Hossfeld bender I use this adjustable top tool a lot for quick bending while working at the forge. Depending upon the thickness of the stock, the post may need a sleeve to make the working distance smaller.  I don’t want the sleeve to rotate on the post. There is a lug welded on he post to keep it at the proper height and a notch is cut out of the sleeve which fits over the lug and prevents rotation.

I cut an eccentric indexing line across the top of the post and sleeve so it is immediately apparent how to place the sleeve on the post so it seats properly.  I also marked some lines with a Presto pen to emphasize the alignment features.  It’s a minor thing but eventually it saves time.

Notch for the post lug
Index line cut and highlighted 
Sleeve in place on bender 
Sleeve won't seat with improper indexing

No comments:

Post a Comment

I don't often check for blog comments, so the best way to contact me is directly: at or