Z-Wire Benders

[David Hayward]

Please can anyone advise me on a reliable make of Z-wire bender for fitting a control rod to a 2mm thick standard Futaba servo arm or equivalent using M2 & M2.5 (soft wire) control rod. I recently purchased an Irvine Super Z-Bend Plier with Navigating Pin T-ZB01 which proved to be totally inadequate. It produced Z-bends easily enough but the short middle section of each Z-bend I formed was only about 1mm which meant that the control wire would not lie horizontally when the Z-bend was inserted through the selected slightly-enlarged hole I had created in the 2mm thick servo arm. I subsequently returned the tool to the supplier with photos to illustrate the problem and was promptly given my £10.75 back.

Looking at other similar makes of Z-wire benders where there is a bit more specification detail provided, e.g. as offered by Prolux, the caveat often quoted in the small print is that they are only suitable for wire thickness up to 1/16 in., i.e. approx. 1.6mm, which is no good to me.

Another option is the Du-Pro E/Z bender wire-forming tool, Model DB 481 with two different sizes of dies included to cover wire thicknesses in the range 1.6 to 2.4mm (Du-Pro also offer Model DB480 for 0.4-1.2mm wire thicknesses). However, bearing in mind they emanate from the USA, UK costs seem exorbitant at around £35, especially as I only need to make one Z-bend for the current model I’m building. Also, customer reviews for this product on Amazon are not particularly encouraging, suggesting that the product is not man enough, particularly at the upper end of its design wire thickness range – the orange plastic element seems prone to breaking or the plastic surrounding the metal die is said to become subject to wear, turning a square hole into a round one such that the product soon becomes useless.

So, are there any other options I can explore for M2/M2.5 wire? I have tried creating the required Z-bends manually but find it is impossible to get enough force with hand-held long nosed pliers and achieve a good Z-bend which gives minimal slack once fitted to the servo arm.

[Engine Doctor]

You could try cutting a slot in a piece of steel plate the same gauge as your wire . Insert wire and bend ,tapping down with hammer to make a neat bend. I have two pairs both unmarked that make excellent Z bends so keep looking . Also look on eBay and the model classifieds even put a wanted add in.  Good luck.

[Denis Watkins]

Swing keeps only need one 90° bend

[DaveyP]

Posted by Denis Watkins on 27/09/2017 19:03:12:

Swing keeps only need one 90° bend

[DaveyP]

Yep that's what I used on the difficult to reach connections

[Geoff S]

You can make a Z bend without special pliers. Just make a 90 degree bend either in a vice or just with big pair of pliers. Then make another 90 deg bend as far away as you want the middle section to be (eg the thickness of your servo arm) then twist the second bend until it's in line with the first.

I have a pair of Z bend pliers I bought from Hobby King as a make weight when I was buying something I actually needed for a project. They were cheap and look cheap but they do the job OK.

I've also made use of swing keepers which only need one bend. What you shouldn't do is have a metal threaded clevis at both ends of a metal push rod. They can gradually unscew without the adjustment changing until one end becomes detached with the obvious result if it's (say) the elevator.

Geoff

[Former Member]

[This posting has been removed]

[john stones 1 - Moderator]

I've the H.K ones as well, do a good job.

[David Hayward]

Very many thanks for all your prompt responses – all noted.

Geoff, Tom & John - the HobbyKing website states that their Z-bend heavy duty pliers, which physically look similar to the Irvine ones I originally purchased, can handle wire up to 1/16 in. (1.6mm); this is the limitation I have already highlighted. HK’s statement doesn’t therefore give me any confidence that their pliers will handle M2 (2mm) and M2.5 (2.5mm) wire.

Dennis & DaveyP - I had overlooked the swing keeper possibility, not having used that option on any model for a long time and since I have only been used to using shortish ones which would not be so suitable for the size of fittings I plan to use on the sizeable ¼-scale biplane I’m currently building. However, the longer keeper type you show in your photos, which I see look like SLEC ones (?), would be fine - so thanks for that.

Geoff – Using a vice, I had already tried the technique you describe re creating two 90^o bends then twisting the second bend to bring it into line with the first, having spotted a YouTube video clip demonstrating it on-line. However, I was concerned (perhaps unnecessarily?) that I had weakened the wire at the second bend due to the final twisting stage. As for your warning about using clevises at both ends of the control rods, I have used that technique for many years on several models without problem but always include nuts at each end tightened hard up to the clevises and check them at least before each day’s flight. This approach has always worked for me.

For my current model build, I was planning to use a clevis at the servo arm end, then a short control rod (M2 or M2.5) to a bellcrank with Z-bend connection and then a closed loop wire system thereafter down to the elevator – hence my interest in Z-bend pliers which would be a nice tool to add to my collection provided it can cope with the wire size range I have quoted. However, if I can’t locate Z-bend pliers which I can be sure will do the job, the swing keeper idea is certainly a good alternative – it’ll certainly of course be cheaper!

[Tom Thomas]

I have the same pair as you David, I find them ok, yes the gap is a little tight but as long as you have the control rod at the same level and angle as the servo arm it's not really a problem, if anything it eliminates slop.

I had forgotten about swing keepers! So easy! That way if there is an angle difference swing keepers soak up the difference fine.

[Nigel R]

" HK’s statement doesn’t therefore give me any confidence that their pliers will handle M2 (2mm)"

 

Don't forget on rolled threads, the rod itself will be around 1.6mm and only the thread portion will be M2.

These sort of pushrods are fine to use in the hobbyking type pliers, I believe it is their intended use.

I feel they are unlikely to be man enough for M3 rods though.

edit: I find they do a great job for standard size servo horns and standard M2 rods. The bends need a quick run over with fine grit emery but are far more consistent and accurate than I can manage by hand. Certainly I don't feel the need

Edited By Nigel R on 28/09/2017 09:29:31

[Denis Watkins]

Maybe too big, but these M3 RC Clevices are used on big stuff

[Engine Doctor]

Threaded clevises at both ends are fine once adjusted lock the thread with a drop of cyano. They can easily be undone at any time by heating .

Edited By Engine Doctor on 28/09/2017 09:49:26

[john stones 1 - Moderator]

Solder these on and use a clevice, come in variety of sizes.

[Wilco Wingco]

Always works for me.

https://www.youtube.com/watch?v=TBJHmDuphJc

[Nigel R]

whoops, end of sentence went awol

"Certainly I don't feel the need"

...to use anything else on the servo end of connections.

[David Hayward]

Thanks for all your follow-up comments.

Nigel R - I am aware that the plain wire part of pushrods rods with threaded ends is slightly thinner than the threaded part so that M2 rods have 2mm gross diameter threaded ends with the plain wire part being about 1.6mm. Similarly, the threaded end of M2.5 rods have a gross diameter of 2.5mm with the plain wire part being about 2mm. See my attached photo below showing test results with the Irvine Z-bender I bought. Note that the two sizes of test rods (M2 & M2.5) described are old pieces which have had the threaded part cut off and so the plain sections of the M2 and M2.5 rods shown represent thicknesses of approx. 1.6mm and 2mm respectively. As mentioned in my original post, I couldn’t get the short middle section of the Z-bends to be more than about 1mm and so I couldn’t get either rod size to lie horizontally in a 2mm thick standard Futaba servo arm; hence, I would have the same problem with a 2mm thick metal bellcrank. Incidentally, for my sizeable biplane, I would prefer to use at least an M2.5 control rod rather than M2 as its more rigid/less flexible (this is in fact what is provided in the kit which is a ¼-scale DB Sport & Scale Sopwith Pup).

Denis - the aluminium M3 clevises you illustrate are, as you say, a bit more heavy duty. To date, I have been a bit put off using this type. I imagine fitting the retaining clip when working in tight spaces within a fuselage could be a bit fiddly. Also, if I ever had to do an adjustment at my club flying field, I can see those tiny clips ending up getting lost in the grass!

To pre-empt anyone who thinks of mentioning them, I originally thought of using a Kavan Z-bend coupler which can be soldered to the plain end of a pushrod (photo attached). These used to be available in two sizes – 1.5mm Z-bend with a 1.7mm ID coupler (ref. 6232) and 1.5mm Z-bend with a 2.1mm ID coupler (ref. 6230). Unfortunately though, it seems than Kavan have discontinued producing the larger size.

Wilco – that’s the YouTube clip I have seen before which criticises Z-bend pliers for the reasons I have described (often producing less than ideal short Z-bend middle section lengths) and advocates the double 90^o bend and final twist technique mentioned earlier by Geoff. Maybe my slight concern about weakening of the wire following the final twist is not justified? I’ll experiment a bit more with this option.

At the moment though, I think I’m tending towards running with the sleep keeper option for attaching the elevator control rod to the bellcrank, with a clevis at the servo end. Use of a standard steel clevis, locking nut and coupler in place of a sleep keeper is of course a possible option. However, a clevis + coupler at the bellcrank/plain wire end of the pushrod and a clevis on the threaded end at the servo would not work so well for my current application - the control rod needs to be bent not far from the centrally-positioned bellcrank in order to reach the elevator servo mounted on one side of the fuselage while avoiding too sharp an angle.

[Nigel R]

David, the Irvine pliers look diferent to the HK / prolux ones I have. All I can say is, the bends the HK one produces work fine on standard hitec & JR horns.

In your application I'd probably use a decent ball link at both ends of a rod, plus locknuts.

[Ron Gray]

You can always heat the rod up first before bending but won't get over the lack of a middle section! Having said that, on large models I now use carbon rods with clevisis epoxied on.

[David Hayward]

I have only just spotted that David Pearce 4 generated a discussion starting at 8/7/14 at 15.57.08 on this forum entitled ‘Problem with Irvine Z Bend Pliers’ which echoes my own – worth a read (NB No hyphen between Z and Bend in the title if you search for these postings).

Nigel R - Yes, on studying on-line pictures of the Irvine and Prolux Z-bend pliers, I can see that the general shape of the jaws are different but, without seeing them both side by side, it’s difficult to determine any difference in the ‘Z’ dimensions within the jaws. If your Prolux pliers from HobbyKing work for you on standard Hitec and JR servo arms which, like, Futaba, are 2mm thick, I can only say that this doesn’t quite fit with the Prolux literature stating that their Z-bend pliers are only suitable for up to 1/16 in (1.6mm) wire! What’s the max. wire size as seen by the jaws of your Prolux Z-bend pliers that you have actually tried and been successful with?

Ball link at both ends in my application? – hmm; food for thought.

Ron Gray – Thanks, noted.

[Martin Harris - Moderator]

I find this rather odd unless (a) Irvine have changed the design or (b) have alternative sizes available...? I'd have thought it unlikely that there would be much manufacturing variance but perhaps you just had a bad pair?

Mine make bends which are slightly over 2mm deep and have always fitted Futaba arms perfectly.

[Nigel R]

"I can only say that this doesn’t quite fit with the Prolux literature stating that their Z-bend pliers are only suitable for up to 1/16 in (1.6mm) wire! What’s the max. wire size as seen by the jaws of your Prolux Z-bend pliers that you have actually tried and been successful with?"

I've only used mine on the small stuff I'm afraid, the usual 1.6mm rods with rolled M2 threads.

I seem to have used the Prolux and Hobbyking names interchangeably, but I believe they are identical.

[Martin Harris - Moderator]

I've just checked my Irvine "Navipin" version and it is really only suitable for 2mm threaded rods but will just about cope with 2.5mm welding rod.

[Peter Miller]

This is one wire joggle bender that I use, It came from a friend in the USA years ago.

[David Hayward]

Thanks everyone for all your additional comments – all noted.

Martin H – Re your Irvine Z-bender experience, yes, all a bit odd. I have checked by test Z-bends which I produced when I had my Irvine Z-bender. Taking the best of the bunch, I find I can just about be persuaded that I achieved 1.5mm deep bends on one or two of them (see photo with a ruler now included), better than the 1mm I’ve previously quoted, but, they still don’t sit at all well in a 2mm thick standard servo arm. I could of course add a small extra bend to bring the main part of the pushrod wire to the horizontal but I see that as a compromise too far. I certainly couldn’t achieve the 2mm+ Z-bend depth that you illustrate with your Irvine Z-bender. Maybe for some strange reason, I have been just unlucky with my particular purchase. However, since for my current build project, I really want to use a 2mm pushrod (M2.5 thread), I shan’t now be pursuing any Z-bender pliers option.