homemade flat hop tuning

[MrInfernal]

Hey guys, 

I just finished my homemade flat hop with a 3D printed arm, eraser nub and modified guarder bucking. All and all, it looked horrible when I put it together, but when I did some test shots, they flew pretty straight without any noticeable side deviation. 

BUT

It seems that I cant fine-tune the bb vertical trajectory, especially at the end of the range. It seems that, either, I have too much hop or too few hop, and also I can see properly what the BBs do after the first half of their flight.

Any ideas of what to do?

 

[Rogerborg]

What hop unit are you using, and how is it adjusted?

Hop units with gears have inherent slop between the gears.  You'll notice that if you rotate the adjustment wheel that it can move quite some way before the gears engage and it applies more pressure to the arm, and vice-versa when you reduce the hop.  To make small adjustments, you have to try and feel for the point where the slop has been taken out.

A rotary hop has a much more direct connection to the arm and (in principle) it should be easier to make fine adjustments.

I say in principle because in practice you may have feeding or air seal issues if you swap hop units.

 

[Adolf Hamster]

flat hops can be very sensitive for hop adjustment, as rogerborg says a rotary style hop can help as they tend to be easier to do very fine adjustment on.

there is a sweet spot, but it's much much less forgiving than a standard hop.

 

[MrInfernal]

My hop-up unit and arm photos below, stupidly I havent taken photos of nub and buckin before instaling them in ?

View attachment 49654

View attachment 49655

 

[Rogerborg]

OK, rotary is good.

Is the hop arm free to move up and down within the unit?  No stickiness at all?

 

[MrInfernal]

Hmm, I will check it when I get back home, but the fit was pretty tight especially the nub could be tad bigger on the sides.

 

[Wo1f]

You could use a softer material for the nub, but that would generally only give you a touch more sensitivity at the beginning of the hop adjustment instead of the end. 

What weight BB are you using? To see at range I use .32 tracers for my <350 FPS guns when ranging them in. Very easy to see your trajectory that way 

 

[Samurai]

I came here to comment to use soft nub but Wo1f was faster.

Use a very soft nub.