Wings of Peril

Did you ever drill out the 1/16” hole in a servo arm with a 5/64” drill only to find that your z-bend or L-bend is a sloppy fit? It’s a simple thing but I’ve been doing a lot of it lately getting new and refurbished models ready for the season - and I hate slop in my linkage! I don’t think the inconsistent results are due to crooked drilling. I’ve tried my drill press.

Here’s what I try to do – but it doesn’t always work. I drill very slowly with the 5/64” and when it’s through the plastic, I back the drill out, trying not to let it spin in the bore. Spinning seems to ream out the hole, resulting in a hole that’s too large. Backing the drill out seems to result in a nice tight fit – sometimes, if I manage to do it correctly. I've also placed the servo arm on a slab of steel - so the full diameter of the drill dosn't go all the way through the plastic- and that works OK - sometimes.

The best thing I had was a 5/64” drill with a hex bit, the kind made to fit an electric screwdriver. I could twist that shank with just my fingers, and then back it out without reaming the hole too large. But I broke that bit – probably doing something dumb with it.

What are some other solutions and methods? Is there a numerical or metric drill that provides more consistent results? What size?

Thanks

LANNYBOB

if its plastic, ive always used an exacto blade to make mine a little bit bigger.

alan0899

G'day Mate,
Another fix is, don't use "Z" bends, I use a combination of ball links & clevises, use threaded couplers to get thread on the rod, no slop, & plenty of adjustment, & you can reuse them, if need be, in other planes.

Ed Smith

Do not use a drill press. Put the drill in a hand held pin vise, turn it by hand.

Ed S.

MinnFlyer

My Feedback: (4)

I sometimes heat up a pushrod wire and push it through the hole. Don't get it too hot or it will melt a large hole. You want it just hot enough that you have to really PUSH it through.

Dr1Driver

I use a pin vice and Z bends and never have any sloppiness problems. Are you sure your pushrod wire is 2-56 size, not 2mm like included with many "Pacific Ring" kits? 2mm is slightly smaller and will cause a sloppy fit.

Dr.1

jooNorway

Using Z-bends sometimes work, other times there might be a lot of slop. Therefore I nearly never use Z-bending any more. One reason for slop is that the pushrod get squeesed in the bends, and when forcing this through the hole in the servohorn the hole expands. Also if the Z is not absolutely 90` in each bend the pushrod might move up/down causing even more slop.
I prefer to make a clean 90` bend and use EZ-links like those: http://www2.towerhobbies.com/cgi-bin...?&I=LXAZC3&P=0

Clean

I just use a piece of the pushrod cut off after a z bend. Cut it at a slight angle with the side cutters and chuck the other end in a hand drill. Then just drill through with that. Blammo, hole exactly the right side, no slop.

Sorry I forgot to tell you guys, I guess. But, you can stick with your preferred processes. Me, I'm gonna go fly. See you in an hour.

daveopam

My Feedback: (9)

I do what Clean does. After using dykes to cut the rod to length. I put the waste in my Dremmel. The cut end from the dykes will drill right through the arm.

David

daveopam

My Feedback: (9)

BTW Clean is still on line??????? I thought you were going flying.

David

Wings of Peril

Duh, I've used the cut pushrod to drill before and just forgot. Thanks, Clean for the reminder. I'll give that another shot. I suspected that forcing the z-bend into the arm holes enlarges the hole. It's just that I get inconsistant results - sometimes perfect - sometimes not. I'll pick up a pinvise and try that too. I aslo like the L-bend and EZ link method and probably use them more than Z-bends. It's just that I finally broke down and purchased a Z-bend plier and have been mesiing around with them lately. Later - great weather today and heading off to the field!

Clean

I wish I was flying. Yardwork, Wallmart and planting today. Trip to the inlaws tomorrow, maybe tomorrow night if the weather moves through.

flipstart

Go to Harbor Freight and get a set of numbered drill bits, they have a set of 60 drills for $13. Never look back, you can drill the exact size hole required for any application, that is assuming you have a set of calipers. Couldn't build without those two tools (numbered drills and calipers). I normally don't buy cheap drill bits, but these seem to work as good as my expensive set.

Flyboy Dave

My Feedback: (21)

....what flipstart said....I would be lost without the calipers and my number drills.

I even keep spares in stock.

FBD.

majortom-RCU

My Feedback: (40)

Lots of good suggestions here, but if you hate slop, you really should get out of Z-bends and get into ball links. Buy Dubros by the twelve-pack from Tower and put them on all your connections. Use well-braced nyrod for smaller planes, or carbon fiber pushrods for larger planes.

camdyson

I second that .... Z-bends belong in the S-bend. Ball links and clevises; problems solved. Same goes for those EZ (?) connectors - the ones with grub screws - I can't believe people still put these on elevators, as is popular in ARF's!![:'(]

Quality ball link at one end, and metal clevis with keeper at the other, and you can simply stop worrying about the whole issue.

Cam (aka Mr Sweeping Statements and Generalizations!)

HighPlains

My Feedback: (1)

Several points -

A correctly sized hole is important in the servo. Buy a Fractional/Number/Letter size drill set. Fractional: 1/16in. to 1/2in. by 64ths. Numbers 1 to 60. Letters A to Z. This is still not complete, since metric is out there, but will cover almost any domestic requirement.

If doing a Z-bend, make sure that the bends are at 90 degrees and tight to the servo arm on both sides to prevent vertical movement.

Push the Z-bend thru the hole with the pushrod pointed at the center of the arm or wheel. This is so that any rounding of the hole's edges are 90 degrees away from the direction that the arm is normally acting on the pushrod for a tighter connection.

JPMacG

My Feedback: (2)

As already mentioned, get yourself a set of numbered drills. They provide more selection in sizes than the fractional drills and they're very handy to have. -or- Grind a pushrod at an angle and use it as a drill bit. I use a drill press without problem.