Originally posted by David Brown
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Re: sprocket wheel. Hopefully we don't end up like this: http://www.truetex.com/sprockii.pdf
But, no seriously, good contribution from all of you. Looked into it more and the film perforations do get very close to the tooth side and if there are any roughness there that can spell trouble. Add to that +- tolerances and the things get worse.
I like Bruce's suggestion.
I searched around a bit and found out that other people also tried the capstan design and had issues:
https://www.chrisgavin.com/2013/02/i...y-6-tooth.html
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Kamel This This is probably the answer. Short pitch could be for negative film.
from Wiki:
Pitch
One of the characteristics of perforations is their "pitch". This is the measurement of the distance between the tops of two sequential perforations. For motion picture 35 mm film and 16 mm film, there are two different pitches—short pitch (camera stocks intended for duplication or printing, and for most intermediate applications) and long pitch (camera stocks intended for direct projection, print stocks, and special intermediate applications). For 35 mm film these are 0.1866" and 0.1870" (4.740 mm and 4.750 mm); for 16 mm film they are 0.2994" and 0.3000" (7.605 mm and 7.620 mm).
This distinction arose because early nitrocellulose film base naturally shrank about 0.3% in processing due to heat, so film printing equipment was designed to account for a size difference between its (processed) input and (unprocessed) output. When cellulose acetate film was developed, which does not shrink, two forms were produced for compatibility with existing equipment.[1]
https://en.wikipedia.org/wiki/Film_perforations
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A slight distraction from the capstan discussion. Here is the capstan mounting hardware info based on Kamel's input:
- Motor mounting screws M3x5mm
https://www.amazon.com/M3x5mm-Philli...strial&sr=1-14
- M2x2 axis motor set screw : https://www.amazon.fr/gp/product/B07...?ie=UTF8&psc=1
https://www.amazon.com/uxcell-Stainl...08G4C2X7601270
- M2x3 insert for motor shaft lock: https://www.amazon.fr/gp/product/B01...?ie=UTF8&psc=1
https://www.amazon.com/a16041800ux07...CMF606RJ9YQYDJ
- M3x4 :
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
-M3x6 screws for the support posts for pulleys:
https://www.amazon.com/Prime-Line-9180421-Socket-Screws-10-Pack/dp/B07D5V2MLP
Last edited by Stan Jelavic; February 13, 2020, 08:22 AM.
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Good point Kamel. Will double check. Adding the M3x6 screws to the list:
https://www.amazon.com/Prime-Line-9180421-Socket-Screws-10-Pack/dp/B07D5V2MLP
Also, updated the list in my previous post.
Received the V10 boards and new front panels plus the cables that were on backorder for a few months.
https://photos.app.goo.gl/XcCxesgSQqVGxtpt8
Robert Held made a really nice front panel and hope he will share it with us. Possibly share the STL file. He also ran the cam with 0.3" spacers and the video that he shared with me looks excellent.
Looking at getting the assembly service and preparing the materials for that. Will probably run qty 20. But first I have to add the frame sync changes and move to V11. The costs are currently at:
- completely assembled board with switches, cables and front panel untested $106 with expensive 2pin black cables.
- completely assembled board with switches, cables and front panel untested $94 with cheap 2pin red cables.
- switch assembly with heatshrink $10
- handling (packaging and mail) $5, does nor include postage cost which is around $4 domestic and $16 Europe.
- Testing $10
Capstan Costs:
- Motor, 3D printed parts, inserts, screws etc unassembled $30
- assembly and test $10
- packaging and shipping $5
- Postage TBD
Can share the cost calculation if interested. Cut the cost down by choosing a single supplier for all electronic components (Digikey).
Last edited by Stan Jelavic; February 13, 2020, 12:55 PM.
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Hi Guys, my last capstan post, I do not have any brass inserts nor any experience with them, so decided to build on Kamel's Toothed S8 Capstan sprocket assembly and draw one up without using brass inserts.
Have replaced the original toothed sprocket on my Wolverine/Hawkeye with the none brass insert model and it works well and does not wobble, may be due to shifting the motor shaft grub screw (used 3mm dia x 4mm long grub screw) closer to the shaft's available length center point (moved by 1.2mm not much I know but the shaft support/bearing surface is only 7mm long).
The screws are obviously not free turning as with the brass insert, there is friction in the threads of the screws but it does not cause any problems. With this approach once one is used to the feel....., the only thing to mention, when tightening the screw that holds the "Front_Pulley_Capstan_S8" I had to use thin nosed pliers to prevent Capstan assembly from rotating.
Have attached the the STL and IPT files.
My USED IPT Files_0.zip
My USED IPT Files_1.zip
My USED STL Files_0.zip
My USED STL Files_1.zip
had to split the files due to size limitations
Regards - Bruce
P.S. Please Note! dimensions are to suit my 3D printer, e.g. 2mm dia bore is drawn at 2.2mm dia because my printer then will print the bore to 2mm. I used black PETG, 0.4mm nozzle, 0.15mm layer height. Have included the Inventor 2019 IPT files so adjustments can be easily made to suit.Last edited by Bruce Davis; February 14, 2020, 02:21 AM.
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Thank you Kamel for providing the original design, it was much easier for me, I just copied yours and made a few minor changes. I used 3mm dia x 6mm long Button Socket Head s/s Cap Screws to hold Front_Pulley_Capstan_S8 in place and a 3mm dia x 4mm long grub screw (in USA they are named Socket Set Screws) to lock onto the 2mm dia motor shaft (3mm long would also do but I only had 4's on hand).
I used PETG because that is what I have on hand, PLA has a low melting point and ABS in my view is not as good as PETG when used in a 3D printer without heated enclosure (although PETG can be more difficult to print due to its stringiness). Would have liked to try Verbatim Durabio, but it is not available in Australia.
Instead of using a square shaped shaft, to enable a thicker wall I changed it to a hexagonal shaft. One version of the Back_Pulley_Capstan_S8 is parallel and the other has a very slight taper on the last half of the hex shaft (for easier mounting).
I also used a slightly smaller OD on the Tooth_Pulley_Capstan_S8, at this dia the S8 film can be wrapped all the way around the circumference without binding on the teeth, and the film unwraps freely.
Regards - Bruce
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Thank you Bruce for the info. I tried to assemble one of them just to see what issues I would be running into. Here is the summary:
- The 2x3mm inserts are a bit large for the capstan back lock hole. Tried inserting it with the soldering iron and the first attempt was a failure. It ended up crooked. The second one went somewhat OK but when the shaft is locked it goes crooked. The main issue is that the shaft hole is too large and there is a significant play. The capstan centering part fits perfectly however.
I might have to do the same thing that you did and redesign it or wait for Kamel to help me with it. Would like to play a bit with Design Spark. Always an opportunity to learn something.
- The 3x3 inserts are too loose so I used 3x4 and installed then with the soldering iron. There is quite a bit of extra material that plugs up the shaft hole and used a drill bit to clean it up. This kinda worked and here is what it looks like.
Will probably go your route because this is a bit too fiddly.
- The new 3x5mm flathead motor munting screws did not work out well. The head countersink does not match the mounting plate and the screws do not bind but stick out too much. So ended up using the M3x3 screws from the following set:
https://www.amazon.com/gp/product/B075C6C4YR/
Waiting for the new parts from Treatstock see if they are any better than PrintaThing.
On anther note completed the firmware and sent the MSP to you today. You do not have to do any rewiring of the switch. The new firmware will run 1fps and 0.5 fps with the existing switch. The rewind will be active only if the run switch is off and the speed switch is in the center. Had to move the rewind check into the run switch off section of the code. If it is in the main loop, the part can not keep up because the rewind check takes several cycles. But that should be OK unless we forget and start scratching our heads why the rewind does not work.
Used the forum instead of private message since other members may be interested in the discussion.
Regards,
Stan.
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Stan, the motor mounting screws I have are M3x6 countersunk heads.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Saddly you need to buy a whole box to get two screws. The "back_toothed_pulley", set screw and insert are M2. I did not know that the first time and drilled it out for a M3. I just recently ordered the M2 inserts and I now have 200!
I still think a friction fit is plenty tight on the motor's shaft. As Bruce said, the printed hole is too small when printed as is, for the "back_toothed_pulley". Easy to get a tight fit. I'm going to print Bruce's batch, and Kamel's when he is done.
Stan, I want to be among the first 20 boards you plan to order, unless that many are taken. Make me #21! Should I find the old list and put a note in there? I want a finished and tested V11.
In other news, My optocoupler failed your tests multiple times. I bought a new one and installed it today. Not only does it work, before this I had to disconnect the sync plug before powering up. That is also fixed, probably caused by the bad switch.
I think the S8/R8 switch is the same part as the claw switch, except the boards are cut slightly different. I'm not going to test that.
If anyone is interested, with shipping, $15 from Wolverine Data. I believe that I fried this and it's unlikely anyone else will have this problem.
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Hi all, Stan thank you very much for the MSP430. I printed a few extra capstan sprocket assy's, if you would like to test, please let me know and I will happily send them to you. Not sure how long post would take but I imagine 10 days or less. I am not surprised your having difficulties with these brass inserts they are very small.
Regards - BruceLast edited by Bruce Davis; February 15, 2020, 02:06 AM.
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Thank you Kamel. I will let you know once I get the parts.
Bruce, forgot to mention that capstan will work in slow speed only. It takes up quite a few processor cycles.
David, I am still far from qty 20 which reminds me to update the qty list. Glad to hear you got it foxed and that the parts are readily available from Wolverine.
Anybody interested in getting the V11 kit, please update your info in the list:
https://docs.google.com/spreadsheets...it?usp=sharing
If I run out of the pre-assembled boards the price will go up significantly. The cost sheet is here:
https://docs.google.com/spreadsheets...it?usp=sharing
Last edited by Stan Jelavic; February 15, 2020, 12:32 PM.
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