Re: Gauging interest in a run of reproduction knob tips


Terry Gray
 

Don't think the original knob is made from bakelite. Bakelite is a "thermosetting" material and it would not be likely that it would ever crack like plastic.  It is definitely a type of plastic (melts with heat applied). Anyway, I am very happy that Evan is considering reproducing them. Should be a lot of interest in this.
    How about also reproducing the LeCroy 9300 series (you might also consider the LeCroy LA314 and similar scopes in that LA300 series--originally designed by Iwatsu) front panel knobs >>I definitely know that these would be VERY popular. The plastic shaft on the encoders break off with the knobs and both pieces end up lost. In my experience you can often repair the encoder and I think that the encoders themselves are still available (part numbers are available in the LeCroy blog history) but the knobs seem to be unobtainable. Have never seen a source for the knobs and have looked for years. You can sometimes find a knob that will work or can be modified to work but they don't match the others.  And these older LeCroy oscilloscopes are fantastic (digital scopes over 1GHz, analog up to 470MHz) and unbelievably cheap compared to original cost (for instance the LA314H originally listed for $14,000 in the 90's)>>> I picked my first LA314H up on Ebay for $99.00 BUT it had CONSIDERABLE problems in the out-sourced power supply). Reply to me if you are interested in any or all of the problems experienced. But most of the problems can be rectified easily IF you catch them early enough. It really gets bad if you wait until disaster occurs (like my first one). These SMPS are great until they fail catastrophically.      Terry

On Wednesday, December 2, 2020, 11:27:46 AM CST, thespin@gmail.com <thespin@gmail.com> wrote:


Hey all,

I've noticed that a lot of the lever knob tips have cracked due to the combination of being made of bakelite and the internal st

resses of the leaf spring. I'd like to do a short run of replacement knobs. I've tried several different 3D printing processes and haven't been totally happy with any of them. In particular, FDM tends to have pronounced layer lines, and small enough nozzles require extremely high melt flow rates restricting the choice of materials and thus colors. I also have an SLA printer, but these resins result in parts that last a few months before cracking due to UV exposure. Thus, urethane casting and injection molding are seemingly the best options. MJF or SLS may be ok but I'm not a huge fan of the texture.

If you'd be interested, I'd appreciate a response to the following survey.

https://forms.gle/U4LUT8LiVHhDk911A

Best wishes,
Evan

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