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FSR Musings
Posted: Wed Mar 11, 2015 9:18 pm
by mhackney
What are folks using the FSR sensors using to attach to the leads of the FSR itself? I've tried 3 different 2 pin connectors (.1") and none hole securely.
Re: FSR connectors?
Posted: Wed Mar 11, 2015 11:45 pm
by Nylocke
I just solder them and put tiny heat shrink over them. Worked so far for 6 of them.
Re: FSR connectors?
Posted: Thu Mar 12, 2015 10:46 pm
by mhackney
Thanks. I ended up doing the same except I soldered on short leads and then installed a 2 pin connector to these leads. It worked well.
I designed some mounts with the "pad" and holder for the FSR for my mini kossel. It has a Smoothie and i want to try 626Pilots' code. I'm using the FSR Endstop Controller, that really makes it a lot easier and the LED green/red feedback for each FSR is nice. I got it all hooked up to test and it seems to be working well.
You'll notice the pad is trlobal, that makes it a lot easier to get a good sliding fit without slop. The triangular bases can can be moved in/out to adjust the radius for the pads to fit into the holders. This worked really well. I have an Orion heated bed and snowflake insulator that overhangs the kossel base.
Re: FSR connectors?
Posted: Fri Mar 13, 2015 8:35 am
by mhackney
Here they are installed. Once I have this working on the mini kossel, I'll do an update for the Rostock. I'm waiting for a couple of Smoothieboards to arrive and one of them is destined for the Rostock Max.
[img]
http://mhackney.zenfolio.com/img/s7/v15 ... 7481-3.jpg[/img]
[img]
http://mhackney.zenfolio.com/img/s12/v1 ... 0469-3.jpg[/img]
This is the little FSR Endstop Controller with one of the sensors triggered (the red LED). I made a little mount for it so the LEDs are visible.
[img]
http://mhackney.zenfolio.com/img/s12/v1 ... 5946-3.jpg[/img]
Re: FSR connectors?
Posted: Fri Mar 13, 2015 1:21 pm
by mhackney
Just ran the first calibration with the FSRs on my mini kossel. Worked perfectly!
Re: FSR Musings
Posted: Sat Mar 14, 2015 1:26 pm
by mhackney
Now that I've installed the FSRs and had a chance to play with Smoothie's delta calibration (G29) and 626Pilot's
cool Heuristic Annealing Smoothieware branch I have some interesting results.
Firstly, the mounts I made work great. However, I initially just used the PLA plunger with no rubber pad like almost everyone uses. I had sanded the surface of the plunger so it was flat. Running G29 game food results but in 10 tests there would be variations of about 4 steps between the lowest and highest values. Today, at the hardware store, I found 1/2" OD neoprene rubber washers with a 3/16" ID. I figure the surface area of the rubber should be fine so I picked them up. After installing (cemented to the the plunger) I ran a G29 and was astounded that the 10 test measurements were dead on 770 steps for all 10 for a score of "very good"! I did this 3 times just to be sure. This really displays how important some form of soft pad contacting the sensor is. I suppose it spreads the force more evenly over the sensor so there are no hot spots. So, use those pads - even these 1/2 washers are very effective and easily found at hardware stores.
Re: FSR Musings
Posted: Mon Mar 16, 2015 5:22 pm
by mhackney
Just a quick update, after putting the rubber washer above the sensor I've been getting excellent reproducibility - every calibration run is exactly the same # of steps. Can't complain about that. I'm still struggling to get 626Pilot's HA code to run reliably even with the GLCD disabled. But the FSRs are a "win" in my book. I am now designing the mounts for my Rostock and the new Smoothieboards were shipped today so I should be ready to convert it to Smoothie later this week.
Re: FSR Musings
Posted: Mon Mar 16, 2015 5:32 pm
by Nylocke
I had no idea rubber would help repeatability. I've been trying to do a rigid no squish system, I went as far as to use M3 fender washers on my MAX. They seem repeatable enough (haven't tried it out with smoothie so I don't have actual data) but the ABS triggers I made for my schools Mini Kossel were horrible. I was getting anywhere from 4-8 steps difference. Thanks Michael.
Re: FSR Musings
Posted: Mon Mar 16, 2015 5:34 pm
by mhackney
I ran enough tests with the PLA plungers w/o rubber and they were good but not highly repeatable. Adding the 1/2" od rubber washer was an instant improvement. I was very surprised myself!
I got these at the local hardware store - neoprene 1/2" OD, 3/16" ID washers.
Re: FSR Musings
Posted: Tue Mar 17, 2015 7:16 pm
by 626Pilot
I just ordered a bag of 100 0.5" OD neoprene washers for something like $10. How are you planning to affix the Rostock mount to the printer?
Re: FSR Musings
Posted: Tue Mar 17, 2015 7:21 pm
by mhackney
Take a look at the STL file I posted about an hour ago in your HA thread. It will screw to the top melamine plate with 2 screws - 1 in each slot. This allows the FSR position to be tweaked so they do not bind. This worked well on the kossel mount I made and this new mount can be used on kossels, rostocks or any printer really.

- Screen Shot 2015-03-17 at 7.24.15 PM.png (150.81 KiB) Viewed 10395 times
Re: FSR Musings
Posted: Tue Mar 17, 2015 10:29 pm
by 626Pilot
I might modify the mount to clamp to the towers. I don't know if the screw holes are all the same across revisions. Mine look a little different from others I've seen.
Re: FSR Musings
Posted: Wed Mar 18, 2015 8:01 am
by mhackney
Not sure what you mean by screw holes? I am going to be drilling new holes to attach these to the top melamine plate with some self-tapping screws.
I'm happy to send source files if you'd like. These are Rhino but I could export in most anything.
Re: FSR Musings
Posted: Wed Mar 18, 2015 6:24 pm
by 626Pilot
I don't want to drill through lexan.

If you can export as STL, that's all I need. Thanks!
Re: FSR Musings
Posted: Wed Mar 18, 2015 6:26 pm
by Nylocke
Isn't Lexan Polycarb? You mean Plexi?
Re: FSR Musings
Posted: Wed Mar 18, 2015 6:32 pm
by 626Pilot
Whatever they made my kit out of in Dec. 2012.
Re: FSR Musings
Posted: Wed Mar 18, 2015 6:33 pm
by Polygonhell
Acrylic
Polycarbonate is a very different beast.
Re: FSR Musings
Posted: Wed Mar 18, 2015 8:26 pm
by mhackney
Ok, I already uploaded the STL in the other (your) thread.
Re: FSR Musings
Posted: Wed Mar 18, 2015 10:50 pm
by jdurand
Lexan is a brand name of polycarbonate. Plexiglas is a brand name of acrylic. Kleenex is a brand of facial tissue. And so on...
