First off I want to say that this post is not an advertisement. I just know that teams have complained for years about $5 PWM cables breaking, so having found a source of cheaper cables I would like to share that information with the entire FIRST community.
After extensive searching I finally found a good source of affordable PWM cables. There is an Ebay seller under the name top_racing2007 who sells various RC hobby items including these servo extension cables, which happen to be the same as IFI’s PWM cables.
This pack of 20 cables costs $8 plus $5 shipping to the US, which comes out to $0.65 per cable. You’ll notice it says 15 packs are available, but if you browse the seller’s store you will find more listings. The cables are available in 50CM and 30CM lengths.
The cables have shrouds on the pins, but these can easily be pried off. You may even want to leave a few cables with the shrouds still on for those times when you need to connect one cable to another because one cable isn’t long enough.
My team has bought several packs of cables from this seller without any problems, and PWM cables have gone from precious luxuries to disposable items.
I hope this information serves the community well.
Maybe I can talk my team into getting some of these, we never seem to have any PWM cables and I constantly have to ward them off from attempting to steal them off of old robots (we try to save old bots for demonstrations).
Another option for teams not wanting to buy IFI’s PWM cables is to make your own. They’re easy to make. All you need is a special crimping tool ($40), the housings (300 for ~$60), the pins (1000 male or female pins for ~$60) and the ribbon wire (100ft for ~$35). So for ~$210 in parts and a $40 tool investment you could make 150 PWM cables at $1.40 a piece.
Yes, they are more expensive than $0.65. However, the trade off is being able to make PWM cables any size you want. This should help clean up a robots wiring.
While browsing DealExtreme the other day, I happened across similar offerings at similar pricing (the base cost for a given number of cables at DX is greater, but with free shipping, the final cost comes out to be on par or better – for example, the per-cable cost of 500cm extensions is about 3 cents cheaper at DX).
Notes:
-> one of my friends ordered some LEDs from DX, and seemed satisfied
-> from reviews, DX is legit but their shipping, while free, is apparently slow
-> “bulk” pricing starts at 3 or more of the same item
-> I haven’t ordered any cables from DX (yet), so I can’t say anything about their quality
Do you have recommendations on where to buy the crimping tool and related parts for making your own PWMs? I’ve never known exactly what those connectors were called? Having them exactly the right length would be a nice way to neaten up the control board.
A very good hand crimping tool is available from Radio Shack, it’s called a D-Sub crimping tool, catalog # 276-1595, listed at $10.99 at Radioshack.com.
This is the correct size for the pins sold by Mouser, for example (e.g, 538-16-02-1114 female and 538-16-02-0115 male).
I’d be careful trying to shorten them up too much. Our electronics guy did just that and every time we had to move something the cable was always too short. It was a pain. But cheap PWM are defiantly a must if you want to try and shorten them to the right length.
Travis is right, Hansen Hobbies has the $40 crimp tool and the connectors and pins and ribbon cable I mentioned in my previous post. Mouser and Digi-Key also sell all the parts you need to make your own PWM cables, but they’re more expensive than Hansen.
No, they’re not breakaway headers, because the pins are long on both sides, not just one. Normal headers have short pins on the side that goes thru the board.
), but aren’t those just breakaway headers?