Links and lengths

[kungpo]

This might seem like a dumbass question, but how do you get link arms to be the correct length, and indeed two of them to be the same length. If I try to get them to be the same length, using calipers, then the ball links don't match up - that is, they don't line up as such. Hope this makes sense.

[xygax]

OK. Calipers (Vernier) i assume. Measure from the centre of the hole. Vario sell a couple of tapered pins that fit on the vernier so that you measure centre to center accuratly without having to judge the middle. You can measure from the inside of the hole but beware the vernier is quite sharp and metal dont score the inside of the ball link holes.

What i think you are gettin at is if you measure one at 55.57 then the other one is 55.51 when the hole is facing the same direction but when it is exactly the same length it looks like its hloes are on the p1ss.

The degree of precission on the calipers is a little more than is required to set the rod lengts .05mm to .1 mm is an probably acceptable difference between the lengths when they are set with the end's so they line up. There is a trim on the raido designed to allow fine adjustment and clear up this type of minor setup issue...

Similar issue:-
On a futaba servo there is an odd number of splines and because of this it is not possable to take a servo crank and fit it exactly 180 deg on both sides of the servo it has to be trimmed.. This would only be possible if there were an evan number of splines......

Regards Steve

[Fixxxer]

you could also get the links as near as you think, pop them on the balls and then measure between the middle of the screws of each ball, this will give you an accurate enough reading.

[kungpo]

Ahh...that answers it - it doesn't have to be as precise at the calipers let it be. As you say, the threads on the links/riods won't allow such fine accuracy.

Thanks!

[robgt]

Generally, the rocket links themselves are the same (as each other) so you can normally get away with measuring the rod length between the links.
It's one of the measurements given in the 600n manual, for example - as there's no guesswork or estimation involved.

Cheers,
Rob

[warboysastro]

I use my digital calipers to make them both the same length, then if they need extending, open each out by a turn at a time.

That way, they stay the same whilst you extend them.

Maplins do a reasonable digital caliper for a tenner.

Cheers - Rob

[kungpo]

I've got the Maplins digital calipers. What I don't get it how to make the linkages *exactly* the same length. If I do, the links don't line up. I'm guessing it's less critical in the linkages that are single, but on the T600N, there are a few that are pairs.

[warboysastro]

Yes, make them the same first. eg. if instructions call for 45mm centre to centre, if they're going onto 3mm balls, make them 42mm inner edge to inner edge according to the caliper. Then try them. If they're too short to fit the heli, lengthen each by a turn at a time until they fit. They then stay the same length as each other. It's not difficult

Cheers - Rob

PS. Sometimes you can't get the lengths absolutely the same, since the ball links are meant to pop on on one face only. In that scenario, just unwind one or the other to have them as close as possible in length.

[kungpo]

well...I guess we'll find out when the time comes to set it up. Then I'll either be congratulated or laughed at...!