Hollow threaded rod or ...

[TheLurker]

... does anyone know where I might get, for purposes nefarious and utterly unrelated to cycling - see pics, some M5 threaded rod with a central bore of 2.5mm?  Hunting around the various DIY barns and what few independent HW shops that are left hereabouts draws a blank.

I've managed to make a couple of short lengths, about 3/4", from M5* coach bolts with a hand-drill, a modicum of patience and chain oil.  Unsurprisingly the bore isn't exactly || to the line of the bolt.  They're *just about* good enough, but *ideally* I need two lengths about 2" to 3" long and the hand-drill technique just won't cut it.

Failing that has anyone got a lathe or pillar drill and could see their way clear to making up a couple of lengths as described?  Beer or other recompense can be arranged.

chr$
Lurk.

LurkOnnaBike : Flickr









*Don't you just love these mixed units?  I do .

[rafletcher]

I assume you’ve considered tube that you then thread externally? I could only find 5 x 1 though, no 5 x 1.25.

[TheLurker]

I could find any suitable unthreaded tube either.

I have dies and taps so threading any steel tube with an internal bore of 1.5mm with enough of a wall to take a solid thread would work, but I'd like to keep to a 5mm OD for reasons of robustness and easy handling of the finished component with dodgy middle-aged eyes. 

I say 1.5mm ID rather than 2.5 because I could then dump the intermediate Al carrier tubes which are a work-around thus making the stooge much simpler. A 1.5mm ID is an absolute minimum.

[Brucey]

a thought; why not just fit a couple of pop rivets through the aluminium plate, and use the centre bore of the rivet as the guide/support you need?

The rivets would have to be the 'non blind' variety, or blind rivets with the remaining part of the centre stub removed. 

cheers

[David Martin]

Or use threaded rivets.

[Jurek]

Have you considered asking Loadsabikes (on here) to make you some?

[TheLurker]

....rivet(s)...

Thanks for the suggestions. Unfortunately rivets aren't a good solution.  They haven't got the length necessary to support the retaining wire close the fuselage so wouldn't provide the bracing / support necessary for a fully wound motor.  That's why, although they're not an ideal solution,  I'm having to use auxiliary Al rod with my short bolts to carry the retaining wire. Ideally I'd like to dump the auxiliary rods as the introduce complexity and fragility.

Have you considered asking Loadsabikes....

I did drop a heavy hint in my OP, but didn't know if anyone OTP was suitably tooled up 
Time for a grovelling PM I think.

[PaulF]

Can't help - but I'm intrigued as to what it is? Obviously a model aircraft but why the holes in that position?

[Wobbly John]

Have lathe but I don't have 2.5mm drill bits that will drill that deep.

[TheLurker]

Can't help - but I'm intrigued as to what it is? Obviously a model aircraft but why the holes in that position?

Have a quick goggle for "winding stooge".  It'll save me boring those here that aren't interested in long winded explanations.

Have lathe but I don't have 2.5mm drill bits that will drill that deep.

If you were able to drill out (for preference) a 1.5mm bore what's the best you could do?  And, supplementary question, how much beer would it take to persuade you to do it?

Now a stupid question from someone who hasn't used a lathe in over 43 years.   Having drilled out to the maximum depth for the drill bit in use from one side would it be possible to reverse the piece in the headstock and, reliably/accurately, drill out from the other side to increase the length of the bore?

[Jurek]

Now a stupid question from someone who hasn't used a lathe in over 43 years.   Having drilled out to the maximum depth for the drill bit in use from one side would it be possible to reverse the piece in the headstock and, reliably/accurately, drill out from the other side to increase the length of the bore?

No reason why you can't do that - but it would be prudent to run the knife along the entire length, while the 'free' end is held in place by a live centre in the tailstock, just to be sure that the bar has parallel sides, so when you turn the job around, it's not pointing east.

ETA - someone who's done some turning more recently than me, will be along to correct me shortly

[bobb]

If I were to do it on the pillar drill, I'd clamp a block of wood to the table, drill a 5mm hole through it, put the rod in the hole (so should be all lined up nicely), swap to the 1.5mm bit and drill as far as possible before turning it over and going in the other side.

Not sure I have any decent 1.5mm bits up to the job though - I normally only drill wood.

I'd go lathe if possible...

[Somnolent]

I assume you’ve considered tube that you then thread externally? I could only find 5 x 1 though, no 5 x 1.25.

I could find any suitable unthreaded tube either.

I've an idea as to where one might find  3/16" x .048/.049"  in stainless steel or aluminium,  maybe even 3/16" x .065"   
5 x 1.25mm (or 5 x 1.5mm) might also be available in stainless, but likely 20 ft length / minimum order charge
PM me if of interest

[TheLurker]

...
5 x 1.25mm (or 5 x 1.5mm) might also be available in stainless, but likely 20 ft length / minimum order charge PM me if of interest

Aluminimum is a bit too soft for what I want and I've no idea how stainless compares to mild steel when it comes to cutting a thread, but 20' is waaaay more than I need.   A foot would be more than enough and allow plenty of spare (about 6"-8") for the inevitable cock-up(s).  Don't suppose this potential source of yours has any scrap 5x1.5mm steel tube that they don't want just lying about eh?

[Wobbly John]

I haven't had time to play on the lathe yet. Would brass be okay - it machines crisply so tends to drill straighter than steel.

By the way, if you only wanted a 1.5mm centre hole, being a cyclist, I'm suprised you didn't just use gear cable adjusters for your trial, short ones...   

[JonBuoy]

Slightly larger than M5 but can you use a valve stem off an inner tube?

[Somnolent]

Don't suppose this potential source of yours has any scrap 5x1.5mm steel tube that they don't want just lying about eh?

No sorry - I might be able to hunt through their scrap bin for the inch sizes, or even persuade one of my former colleagues to just lop off an end as a 'sample'.

But all the metric stuff is in another place to which I have no privileged access (hence the likely 20' minimum) 

[TheLurker]

I haven't had time to play on the lathe yet. Would brass be okay

IIRC brass keeps a thread better than aluminium so it's got to be worth a go.  Will send a PM.

By the way, if you only wanted a 1.5mm centre hole, being a cyclist, I'm suprised you didn't just use gear cable adjusters

Haven't got any spares and absolutely nothing suitable in any of my (many) "bits that will come in useful - one day" boxes.

No sorry - I might be able to hunt through their scrap... ...a 'sample'.

Thanks for the thought, but I wouldn't want anyone to risk even a warning for doing something like that.  Jobs are hard enough to come by as it is.

[Wobbly John]

I took a few minutes to have a play on the lathe at work.

It is just possible to get through 2" with a 1.5mm drill, by drilling from both sides. 

As I suspected, our kit isn't accurate enough to get the holes to meet perfectly - it will only let something about 1.2mm pass (about 0.1 - 0.2mm out in 25mm). 

[TheLurker]

Thanks very much for taking the time and trouble to investigate. It's much appreciated. Sounds like good results to me.

I think, allowing for the alignment issue you noted, a 2mm bore in a 2" rod should work with a 1.5mm wire.  It'd  mean there'd be almost no unsupported retaining wire regardless of fuselage width so the little bit of slop around a 1.5mm wire wouldn't be a problem.  It might even be useful to allow for "manufacturing"* tolerances in the frame arms' rod mounting holes.

If you give me a buzz ('phone No. in PM) we can sort out the hows and whens.

chr$
Lurk

*Read : Lurk's bodging.

[Crumbling Nick]

Can't help - but I'm intrigued as to what it is? Obviously a model aircraft but why the holes in that position?

My guess is a Hurricane, possibly K5083. I too am curious about the purpose of the metalwork.

Sadly I can't help with OP's requirement without trying to redefine the spec. & it's too late for that.

[TheLurker]

My guess is a Hurricane, possibly K5083 ....

Close, oooh very, _very_ close, but not quite.  *Slips on anorak*  It is K5083, but K5083 wasn't a Hurricane it was a prototype. It was known by various names usually "Monoplane Interceptor" or "Interceptor Monoplane" sometimes even "Fury Monoplane".  The type name "Hurricane" was approved for the production aircraft.  However, idiotic nit-picking aside, K5083 was in all respects a Hurricane.  There were remarkably few changes from prototype to production and most of those were concentrated on simplifications to make volume production simpler. So, yeah it is a Hurricane.

.... I too am curious about the purpose of the metalwork.

Winding Stooge. 
A framework to anchor a rubber powered model at the motor peg so that the motor can be stretch wound by a single person.  Commonly a piece of Al tube is used as the motor peg and a stiff retaining wire is pushed through the stooge's uprights and the motor peg.  The stooge is anchored to the ground / any convenient immovable object.   

The metalwork in mine is to allow for varying widths of fuselage and still provide support for the retaining wire up to the fuselage so as to minimise bending movement in the retaining wire whilst the motor is being wound.  Threaded rod with a fine bore is ideal for this as it can be wound in/out of fixed width uprights to suit fuselage width.  The additional Al. tubing in my version is because I was unable to drill out coach bolts accurately enough over a long enough distance to provide the required support.

Varying the width setting of the frame uprights wasn't an option.  See below.

Sadly I can't help with OP's requirement without trying to redefine the spec. & it's too late for that.

The spec. (ha ha ha) was largely determined by materials to hand, materials that could be obtained from local DIY barns, my limited woodworking and machining skills and limited workshop facilities.

[Crumbling Nick]

Thanks for the explanation. I did Google look up "winding stooge" this morning before I read your reply. I now have a reasonable understanding of the function. However I'm still some way from a detailed understanding of how your device works.

I won't say that it's impossible to make what you've asked for, but am starting to think about changing the spec.

So forgive me for asking lots of silly questions:-

Is the motor peg the bit of alu. tube through the fuselage between the big discs in your pic? Is it replaced for flight(I can't imagine how, but if not, its weight will already have been optimised, so 2mm bore is beyond question)? Is it held in place solely by friction? Is the length dictated by the vagaries of the winding process, & the detailed design of stooge?

What is the purpose of the discs/oversize washers on the ends of the lengths of thin-ish alu. tube? Is it only to stop the motor peg from walking sideways while winding, without damaging the fuselage?

How do the brass bits(presumably ex electrical "chocolate block") work? I might guess about the inner ones, but have no idea about the long-handled outer items.

What is your sequence of set up & operation in the field?

Do you need to accomodate different fuselage widths on the flying field or is it only one model for a day's flying?

And finally, thinking about solutions before understanding the problem , how difficult would it be to change M5 to M6, or even M8 (brass bits...)?

Please feel free to choose which questions you answer .

[TheLurker]

> Please feel free to choose which questions you answer .
I've got nothing better to do right now so I'll have a go at all of them.

> Is the motor peg the bit of alu. tube through the fuselage between the big discs in your pic?
Yes. 

> Is it replaced for flight....
No.  It anchors the rear of the motor.  The other end drives the prop. Think glorified elastic band.

> ...weight will already have been optimised..
Yes.  Aft of the CG so weight kept to an _absolute_ minimum. Long winded explanation as to why available.  Send SAE and postal order for 2/6^d to Lurker Industries Product Support Dept.

> Is the length dictated...
Mainly weight as above.  Needs to be as short (and therefore as light) as possible but leaving enough sticking out either side (typically 5mm or so) so that a late middle aged fumble fingered fool can extract it to fit or replace the motor.

> What is the purpose of the discs/oversize washers on the ends of the lengths of thin-ish alu. tube?
Nearly right. It is to stop damage to the tissue if the model moves on the retaining wire.  The motor peg shouldn't move but it is possible for the peg & therefore model to slip sideways on the wire.  The aux. tubes and their discs wouldn't be necessary in a 5 (or 6, 7, VIII) mm threaded tube set up.

> How do the brass bits(presumably ex electrical "chocolate block") work?
Yes ex-chocolate block.  Simply to lock the auxiliary support tubes at the right width.

> What is your sequence of set up & operation in the field?
a Remove motor peg from model.
b Fit rubber motor in model hooking rear with motor peg.  See also "stuffing stick" or "pushing stick".
c Stooge on the ground. Tent peg or other bit of metal banged through the hole provided for that purpose. 
c Mount model in stooge as per pic.
d Hook winder to prop. end of motor. Welly on the turns.
e Carefully hook prop / nose block assembly to motor instead of winder. 
f Remove whole from stooge carefully. Holding prop to prevent motor running. 
g Chuck model in the air and watch it fly.
h If landing soft enough repeat from c.  Depends on outcome of g.  <--- There's a bad joke in there if you look hard enough

>  Do you need to accomodate different fuselage widths on the flying field ...
Yes.

>  how difficult would it be to change M5 to M6, or even M8 (brass bits...)?
Werl... I haven't got an M8 drill bit for the uprights and Wobbly John has already been experimenting with 5mm brass rod...

[Crumbling Nick]

snip...

A bit of background might help. I built & flew model aircraft about 6 decades ago & rubber power was the easy option. A K5083 paint job was part of that. I didn't have easy access to suitable flying fields, so my interest went in other ways. However I did see FW-TSS take off on telly (merci au  ingenieur de la S.N.E.C.M.A. et sa femme dans l'apartement au dessous) & GB-SST live at Filton with full sound effects, so I didn't lose interest entirely.

> Is it replaced for flight....
No.  It anchors the rear of the motor.  The other end drives the prop. Think glorified elastic band.

Ok, badly put question. What I meant was Is it "boilerplate" for ground activities, or minimal weight component for flying.. Also, as I might have said, I can't imagine how a "flying weight" peg could be inserted into a fully wound motor to replace a "heavy ground-only peg", but if you can do it at the prop. end, then it might be possible further aft.

> ...weight will already have been optimised..
Yes.  Aft of the CG so weight kept to an _absolute_ minimum. Long winded explanation as to why available.  Send SAE and postal order for 2/6^d to Lurker Industries Product Support Dept.

> Is the length dictated...
Mainly weight as above.  Needs to be as short (and therefore as light) as possible but leaving enough sticking out either side (typically 5mm or so) so that a late middle aged fumble fingered fool can extract it to fit or replace the motor.

I had forgotten the difficulties of replacing the motor. That's probably because I only replaced when it broke. I don't remember repairs to the fuselage, so suspect my motors were close to "toy" category.

> What is the purpose of the discs/oversize washers on the ends of the lengths of thin-ish alu. tube?
Nearly right. It is to stop damage to the tissue if the model moves on the retaining wire.  The motor peg shouldn't move but it is possible for the peg & therefore model to slip sideways on the wire.  The aux. tubes and their discs wouldn't be necessary in a 5 (or 6, 7, VIII) mm threaded tube set up.

> How do the brass bits(presumably ex electrical "chocolate block") work? I might guess about the inner ones, but have no idea about the long-handled outer items.
Yes ex-chocolate block.  Simply to lock the auxiliary support tubes at the right width.

I have re-inserted my original attempt to explain why it still isn't "simply" to my antique brain.

> What is your sequence of set up & operation in the field?
a Remove motor peg from model.
b Fit rubber motor in model hooking rear with motor peg.  See also "stuffing stick" or "pushing stick".
c Stooge on the ground. Tent peg or other bit of metal banged through the hole provided for that purpose. 
c Mount model in stooge as per pic.
d Hook winder to prop. end of motor. Welly on the turns.
e Carefully hook prop / nose block assembly to motor instead of winder. 
f Remove whole from stooge carefully. Holding prop to prevent motor running. 
g Chuck model in the air and watch it fly.
h If landing soft enough repeat from c.  Depends on outcome of g.  <--- There's a bad joke in there if you look hard enough

OK some un-asked questions answered, e.g. you don't wind motor out of model.
However in/between sections c,c,d,e,f there is enough detail missing that I still don't understand how & when you assemble the components in your first picture.

>  Do you need to accomodate different fuselage widths on the flying field ...
Yes.

Thanks. Exchanging parts in the field can be ruled out. They would inevitably get lost in grass. That eliminates some alternative design ideas.

>  how difficult would it be to change M5 to M6, or even M8 (brass bits...)?
Werl... I haven't got an M8 drill bit for the uprights and Wobbly John has already been experimenting with 5mm brass rod...

8mm drill bits are not too hard to find. However old hand drills such as I used for model-making often had chucks no bigger than 1/4", which should accomodate 6mm. But as I said last time " thinking about solutions before understanding the problem ".