One of the lessons we have learned over the past two years is that our team is not capable of using the open frame US Digital encoders reliably. We have gone through handfuls of them, and no matter how careful we handle them, they always go bad at the most inopportune times. Looking through past posts, other teams seem to be having similar experiences. Doing some research shows that the best teams have switched over to using the sealed versions of these encoders, with ball bearing supported input shafts. As a summer project, we are going to try this out.
I just got a quote from US Digital for their S4 encoders. In small quantities, they are nearly twice as expensive as the E4P encoders if purchased from AndyMark. Like most electrical components, increasing the quantity ordered decreases price rapidly. We’re looking at getting part number S4-120-250-N-S-B. I’m hoping I could put together an order of at least 50 of them, which would get the price down to $48.60 each. Would any other teams be interested in going in on a group buy of these encoders?
We’ve used the “H” series this year an in previous years with good success.
It also appears that the S4 is no longer available, or looks like it’s being replaced.
I want to ask however, when you got your price quote did you tell them you were a FIRST Team?
They do give a discount to FIRST teams, but you have to ask for it.
IIRC the discount was about 25% on the encoders only.
The discount was moving to the next price-break, so depending on quantity, the discount percentage varies. I was pleasantly surprised the last time we put in an order, but yes, you need mention you’re a FIRST team to get the discount.
There are many options for encoders once you decide to spend some money. Is the US Digital The best buy. What CPR would most teams want to use. I’ll Throw this out for thought. CUI makes the AMT102 and AMT103 encoders. Digikey link hear. http://www.digikey.com/PTM/PTMPartList.page?site=us&lang=en&ptm=5586
Now they are meant to mount on a shaft like the current US Digital that Andy Mark sells. The big difference is that they can be set to many different CPR up to 1024. You can turn these into a sealed unit with shaft. We made a base plate out of polycarb in the shape of the AMT102 base. In the polycarb base we mounted 2 precision ball bearings for a 1/4" stainless shaft. The programmers played with them last fall and they seamed to work well. We have not used them on a robot or really given them a test. Other teams have posted that they worked well. Could a run of base plates be done to add shaft capability to them? Then all that is needed is some shaft and bearing. I believe the bearing were about 5$ apiece. Is this an option?
I did mention that we are a FIRST team, and the discount is to move up to the next price break point. So if we order 50 units, we are getting the 100 unit quantity discount.
Everyone else, it would be very helpful if you could edit your posts and add the quantity you are looking for. When we reach a total of 50 units, I can make arrangements for placing the group order.
All,
I got a PM suggesting we take a look at the Grayhill encoders, as well.
The equivalent Grayhill encoder seems to be the series 63R.
There are two advantages of the US Digital S4 series over the Grayhill Series 63R:
Max RPM. S4: 15,000 63R: 5,000
Size. S4: .85" dia x .50" thk 63R: 1.25" dia x .50" thk
Please note that the US Digital S4 encoders are enclosed, and have a ball bearing mounted 1/4" dia input shaft. These are NOT the E4P encoders sold by AndyMark. The E4P series are the ones we have had problems with.
The S4 is currently listed on the US Digital website as:
The S4 is not recommended for new product development. Please contact US Digital support at [email protected] for more info.
They won’t let you build a part number or order online like they will with their other products. Any idea what the future plans are for this item? I was considering using one, but don’t want to pick something that will be obsolete soon.
Also you wouldn’t want to use something that isn’t considered COTS anymore.
That being said, we’ve been pretty invested in the S4’s and have a decent backcatalog of them. It’s a great product, I just wonder what they’re doing with it.
Just talked to the customer support rep at US Digital. She said the message comes up because the stock on the modules is limited at this time. She assured me that there are no plans for the S4 or E4P encoders to be discontinued. They are working to resolve the inventory issue, but plan to continue to supply them to FIRST teams.
I get the feeling that they might not be able to support an order of the magnitude necessary for the module to be incorporated into a consumer product with volumes of tens of thousands, but have no trouble supporting our small quantity orders.