Lynxmotion Tech Support

Do you read...

_________________
Eric Nantel
Qc Canada

Always liked Robot... Now i am learning to make some...! Wonderfull...

Compatible servos have been listed. What more do you expect?
It would be impossible to make a list of all the servos that DONT FIT!

The brackets were designed for Hitec standard servos, and it's never implied otherwise.

Other servo ranges may carry a different "standard size servo" to there specifications to what they call standard.

You cant blame the product because the servo you chose doesn't fit.

_________________
Jonny Poole,
Freelance Concept Art & Animatronics, 3D Art and 3D Modelling, as well as Physical Modelling, Mechanical design, and illustration.
http://www.innerbreed.co.uk/
Create, Innovate, Inspire.

Feedback is appreciated and ideally would be something we would try to work towards. To give you some additional information: It would depend on which servos; the most popular we have seen (and carry) are Hitec, Futaba and GWS. As Jim discovered ages ago, Hitec servos are very high quality, there is a selection of servos in a specific size range (which allow for a variety of speeds and torque but retain the same dimensions), the specs are readily available and support is excellent. The downside of course is that there are other similar servos available on the market at a lower price. The comparison might be a Toyota / Honda vs. a Pontiac / Chevrolet. Modifying the design to accommodate one or two additional (good quality) servos is actually harder than it might seem.

We are currently testing a $3.50 (retail) servo from China (and new brackets) and comparing it to an HS-55 at $10. The height is off by less than 1mm and as such, the two are not interchangeable. If we chose the larger servo, the dimension of the bracket ensures that the smaller servo does not get enough support. FYI: If we were to release a product using this other servo, it would likely not be under the Lynxmotion brand (it was under development before the takeover).

Systems like Robotis, Robobuilder etc. only allow for a very small number of servos, so the fact that the erector set includes not only room for a variety of Hitec servos, but also in three sizes, is a step ahead of the competition.



We'll see what we can do. In order to mount a servo to a bracket, the dimensions need to be quite precise, so if even one dimension is even slightly off, there's a good chance it won't be compatible.

Appreciate the feedback - keep it coming!

_________________
Coleman Benson
Lynxmotion
Imagine it. Build it. Control it.™
http://www.Lynxmotion.com

So write that! That's all I'm asking. I don't understand why you think it wouldn't be better written that way. Add the word "Hitec" in front of "standard" -- done!

Regarding the GWS warning: I'm not using those servos. The servos I'm using are not "significantly oversize" -- we're talking a difference of about 2 mm in the bottom-of-tab to top-of-horn measurement.



I'm not blaming anything; I'm trying to make the catalog precise enough so that future purchasers will have an easier time figuring out what will work and what won't. I'm not the first person to try this out and find it doesn't work.

FWIW, "standard size servo," in regular RC circuits (which is where these servos come from), means that the servos drop into the appropriate steering and throttle and other control positions, and that the hole pattern matches. This is why I think using only the term "standard size servo" is rather too vague for what the product requirement actually is.

Hi, jwatte,

You profess to seek precision in terms. Those who know me on this forum, know I yield to no one in the precise use of language. I wonder if you are familiar with the term "Pyrrhic victory." Could that be what you are seeking here?

Just a thought.

_________________
Ted, RoboTed
Never quite finishing means never having to admit failure!

(coming back to this thread) I'm not after a "victory" at all; I'm trying to make the world ever so slightly better for those who come after me. No sense in even one other person running into the same problem when the fix is literally so simple as to add a single word to the description ("Hitec standard servos.") A warning saying "other servos are likely to not fit" would be even better, but for some reason I still don't understand there's a big resistance in this thread to doing that.

In the best of worlds, a precise measurement diagram for the brackets themselves would be ideal. The best sites on the web (mcmaster-carr, digikey, budindustries, etc) list all the exact measurements and other specifications of all their parts, and it's what I look for in a quality vendor. Honestly, the cost of the two sets of brackets I bought just to try it out is lost in the noise, but seeing all this resistance to trying to IMPROVE THE PRODUCT DESCRIPTION is what I don't understand. Why resist making the world a slightly easier-to-live-in place by making a basically free text edit?

I agree that the exact measurements should be published also. This will help provide customers with an accurate dimension that will stop any confusion and will mean others won't spend good money on testing them to see if they fit.

There is a thread that's open asking what people would like for 2013. Maybe post your concern there.
Id like to see these details published along with a warning for any servos like this on for example, that don't fit.

Good luck with your venture.

_________________
Jonny Poole,
Freelance Concept Art & Animatronics, 3D Art and 3D Modelling, as well as Physical Modelling, Mechanical design, and illustration.
http://www.innerbreed.co.uk/
Create, Innovate, Inspire.

Hi, Jwatte,

Now, I must admit that I have fully supported your desire for dimensional data and more precise specifications all along. Currently, it appears the only way to acquire the dimensions without purchasing every type of part, would be to download the 3D files, load them into an expensive CAD program, and let it auto dimension the drawings for you starting with a known dimension like the servo horn mounting pattern. Not an ideal solution.

Didn't really think you were trying to win a battle, but I like your current post as more dispassionate and thus more persuasively written. Thanks for taking the time to restate.

Ted

_________________
Ted, RoboTed
Never quite finishing means never having to admit failure!

I hate getting into the Frye about this


Actually you can download them and use any of several free CAD packages out there to view these files... For example Wings3D... I have 3 or 4 of such packages installed on my machine, that I use to convert one format to another in order to show 3d images in the DipTrace 3d Preview... Or course they may be free, but if you are like me, may take you a long time to figure out how to use them

JWatte: I understand your desires here. Personally I think their description is fine as Lynxmotion for the most part has only sold Hitec servos and the brackets were designed around these servos. There was some mention of some servos known to have issues. Personally I would not expect a company would be very motivated to say you can use these cheap knockoffs instead of buying stuff from us... However now that Robotshop owns Lynxmotion, they probably should mention which of the servos they sell fit or don't fit...

Also my guess is that if too detailed of specifications are given the more likely a cheap knockoff of the brackets will be made. And they won't even have to buy one to make it.

But back to topic at hand...
If I take out my digital caliper and measure a C bracket. I see the width on the inside of the brackets is about 1.95" and to the exterior is about 2.1"... I cold probably get out a GP bracket and measure as well. From that you may be able to figure out if a servo fits or not... Looking at the diagram that DialFonZo posted earlier, you could probably calculate if they would fit or not. First you would need the H measurement to see if it will seat all the way down. If you are using a bearing, you will need to take the width of the nut into account as well. Then you need to check how far up it extends from the seat (Probably The G measurement in the diagram plus the width of the Servo Horn). From this you could calculate the height of the whole assembly (height of GP bracket from outside of bracket to top of seat, plus the measurements and it should hopefully come out pretty close to maybe 1.9". Then assuming that shaft is in the right place on the servo (B measurement), it may work...

This sounds too much like work for me, so personally I would rather stick with servos, that I know work...

Sorry about this dribble
Kurt

We certainly appreciate the feedback. There is always room for improvement. We quickly added "Hitec" to the Servo Erector Set description and each of the three associated categories: http://www.lynxmotion.com/c-73-servo-erector-set.aspx
We'll be going through each product to determine which are absolutely restricted to Hitec servos and which are more "grey zone" such as the C brackets where the dimensions can vary a little and adding "Hitec" where needed.

With regard to the dimensions, there are two important factors:
1) The brackets were not originally created in 3D CAD
2) Providing the dimensions makes the work for copycat manufacturers much easier.

We often get requests from students looking to make a 3D drawing of their project, and the community has helped by providing a number of 3D CAD models. However in order to know if a servo from another manufacturer is compatible with a bracket, there are a LOT of dimensions to consider with the servo and the brackets as well. Consider adding a request for a) 2D dimensional drawing and/or b) Additional 3D CAD models. We'll see how the community reacts and get their feedback regarding point #2 above.

Keep the feedback coming.

_________________
Coleman Benson
Lynxmotion
Imagine it. Build it. Control it.™
http://www.Lynxmotion.com

Thanks for updating the page to say "Hitec," I think it's an important step forward.



I don't buy that argument at all, for two reasons:
1) I think we can all agree there is no secret IP here. There might be copyright, there might be trade dress, but those are not secret.
2) The trick is in execution, not in design -- running a store, and getting customers to come back.

And, by the way, making sure that paying customers get the information they need to make a purchase decision is an important way to make paying customers come back.

Check out these specifications:
http://www.budind.com/view/Plastic+Boxe ... Enclosures / http://www.budind.com/pdf/hb11591.pdf

Or these specifications:
http://www.mcmaster.com/#shaft-collars/=k1rllw / http://www.mcmaster.com/#cadinlnord/6433k13/=k1rmc6

(or, really, any part page from those catalogs)

These are from well-known, large, companies that are known to go out of their way to serve their customers, and thus are doing very well. Copy-catting isn't solved by making it harder for paying customers to find information.

Then again, it's not my company, and you can do what you want, but I can also choose to do more business with companies that are more responsive to requests for information I need.


When it comes to "sticking to servos known to work," that's OK if you're buying a full system. Personally, I had some spare servos of a particular type, and was looking around for various things that could fit them, so in the category "have servo, will buy bracket." Also, Lynxmotion is not the only store that sells these brackets -- the exact same description is found in other places on the web at various resellers (Trossen Robotics, for example.)