Would this Encoder work? and Encoder Recommendations

[Type]

My team is looking to use encoders this year and I know a shaft encoder would work well so you could tap a hole in like hex shaft then just insert the encoder and it would work, but what encoders would people recommend? I've hard US Digital a lot. Would an encoder like this work, or would something else work better?

http://www.ebay.com/itm/NEW-US-DIGIT...AOSwfZ1WaMQ 7

[SenorZ]

It would work. But how are you keeping it from losing contact with the hole in the hex shaft? Pressure fit? That would make it hard to swap out if needs service.

See if you can pressure fit a gear on to that shaft, and another on the hex shaft. Mount it gear-to-gear.

[Type]

Originally Posted by SenorZ

It would work. But how are you keeping it from losing contact with the hole in the hex shaft? Pressure fit? That would make it hard to swap out if needs service.

See if you can pressure fit a gear on to that shaft, and another on the hex shaft. Mount it gear-to-gear.

I didn't think of that. I've heard of people using part of surgical tubing I believe so it can turn, but a gear may work even better.

[GeeTwo]

We have also used shaft couplers to connect this sort of encoder to a drive shaft. If you are connecting a 1/4" stem to a 1/2" shaft, you will need a significant filler. A 5/16" nut takes a 1/2" wrench, so that'll get you most of the way there; a bit of tubing can do the rest.

[Eric Scheuing]

Originally Posted by Type

I didn't think of that. I've heard of people using part of surgical tubing I believe so it can turn, but a gear may work even better.

We've used surgical tubing before and it works great. Drill and tap hole in the end of the shaft for a screw that comes relatively close to the diameter of the encoder shaft. The hole should be relatively centered but don't worry if it's off slightly. Cut the head off the screw, slap a jam nut of that sucker and Loctite it in place. Then attach the surgical tubing to both your screw and encoder and use zip-ties to clamp it on. You want to use as short a run of tubing as possible to eliminate any concerns for losing ticks to the torsion of the tubing, but you don't necessarily want the screw to butt up against the encoder shaft, since then concentricity DOES become a concern. Shoot for 1/4", maybe 1/2" gap.

This worked well for us. If you want to mount the encoder directly to the shaft, I have a suggestion for that too, but it will require me to break out my crappy paint skills. Just let me know if you're interested!

[tr6scott]

http://www.ebay.com/itm/160817272031...%3AMEBIDX%3AIT

Maybe worth a look for $10, much lower resolution though.

[Mark McLeod]

That one Scott looks like a panel mount encoder intended as a human operated thumbwheel. Generally that means it isn't designed for use at speeds and stresses drive mechanisms see.

[Type]

I've heard of teams using like US digital s4t (if I remember correctly), where would you purchase one of these? I couldn't find any on Ebay...

[adciv]

Originally Posted by Type

I've heard of teams using like US digital s4t (if I remember correctly), where would you purchase one of these? I couldn't find any on Ebay...

Either andymark or direct from US Digital. We placed an order direct a few years ago, we probably will this year as well (discount for bulk ordering). I'm still trying to find an alternative.

[Type]

http://www.usdigital.com/products/s5
Sorry for so many questions, but would an encoder like this work? I noticed there were for sale here on CD by another team, the connectors just look a little different.

S5-5000-250-IE-S-B to be specific.

[billbo911]

I purchased one of these the other day for a personal project.
I wanted 360 PPR, and relatively low cost, so this fit the bill.

When it arrived, I was STUNNED by the build quality!! It is a VERY well built encoder! That said, it is a lot larger than most encoders of this style. It is approx. 1.5" dia. and approx. 1.4" long. I also found that using 4.7K ohm pull up resistors with it made it very stable with my Arduino.

BTW, you can get this in a couple more PPR values.

[Type]

Originally Posted by billbo911

I purchased one of these the other day for a personal project.
I wanted 360 PPR, and relatively low cost, so this fit the bill.

When it arrived, I was STUNNED by the build quality!! It is a VERY well built encoder! That said, it is a lot larger than most encoders of this style. It is approx. 1.5" dia. and approx. 1.4" long. I also found that using 4.7K ohm pull up resistors with it made it very stable with my Arduino.

BTW, you can get this in a couple more PPR values.

So how does PPR affect the code when using a drive train? I've seen some that are rated for like 5k and others that top out at 360. Im assuming you would use one that hits 5k for a shooter, but would a 360 CPR (or PPR) be enough for a drive train to be accurate.

[adciv]

Originally Posted by Type

So how does PPR affect the code when using a drive train? I've seen some that are rated for like 5k and others that top out at 360. Im assuming you would use one that hits 5k for a shooter, but would a 360 CPR (or PPR) be enough for a drive train to be accurate.

On drive train, it depends on what you're doing. We use 250PPR and its still overkill. I think 1 pulse corresponds to 1mm of travel but that can change on if you are using the input or output to the gearbox.

For shooters, we've typically use 2PPR. When you've got a wheel spinning at a few thousand RPM, you don't need many counts per rev to get an accurate speed. A 5kPPR would amount to over 2 million pulses per second on some shooters we've used.

[billbo911]

Originally Posted by Type

So how does PPR affect the code when using a drive train? I've seen some that are rated for like 5k and others that top out at 360. Im assuming you would use one that hits 5k for a shooter, but would a 360 CPR (or PPR) be enough for a drive train to be accurate.

Choosing what PPR you want to use is like many things in engineering, it depends.
Generally speaking, Low RPM favors higher PPR and vice verse. That is a GENERAL rule, not a hard and fast one. Again, it depends. It depends on what you want to do, control speed, distance, or both. What also plays into the decision is what control method you are using. There are trade offs with every choice.
The best thing you can do is test out different approaches during the off season.

[MoistRobot]

Another mounting option for this encoder is to drill a slightly loose hole in the end of the drive shaft to fit the encoder shaft, then cut a slot in the end of the drive shaft to split it and use a clamping shaft collar to hold the encoder securely in the end of the shaft. Works well and can remove/swap the encoder with ease.