Rotor head for RC helicopter

[RC Heli adict]

G'day guys,

My hobby is "large-ish" radio controlled scale helicopters. I have a lathe and a milling machine - but lack the ability to machine complex parts. Normal turning and milling I am fine with. I draw in 3D using AutoCAD...
My current helicopter project requires a scale rotor head. There are no scale looking heads available for my particular model in the size I am after.
The cost to have these parts made by CNC companies is out of the question.
I have uploaded some images of the parts I need.
I have a RapMan 3D printer and have 3D Printed the parts in order to check the "fit".

The reason I am "here" is to get some advice on converting my milling machine to CNC. Will I be able to CNC mill the parts in the images? I expect there may need to be some manipulation of the part and maybe do the CNC in stages... Also I may need new attachments for my mill - that is fine, I have a rotating table with optional dividing plates - and vices, slitting saw and the usual collets and cutters....

My mill is a Hafco HM46 (I think this is similar specs to the HM45)

Also, can anyone recommend a supplier or have a parts list of components I need to convert my mill...

I have also attached a picture of my Blue Thunder heli if interested....

Any advice appreciated.

Thanks

Jim

[rowbare]

You should be able to machine those parts though a 4th axis might come in handy. You will have to pay attention to radiuses especially in the pockets. Some of the corners you show can't be milled for instance the inside corner we see at the top right of the hub. CAM and fixturing will certainly be a challenge but I am sure you are up to it!

There are a lot of RC heli enthusiasts here. Have you seen this fairly recent thread? http://www.cnczone.com/forums/tormac...r_tormach.html

good luck!
bob

[RC Heli adict]

G'day Bob, thanks... I modeled the parts from photographs so a couple of minor mods to make it easier to CNC probably won't matter too much. I doubt anyone else will notice if I remove a radius or two.

I have an HM46 (HM45) mill - would you know the best starting point to find components to convert my mill to 4 axis CNC? - maybe a link on this site to save me search time... I will need to install ball screws. The machine has metric graduations so I will need metric screws.

If you can provide a link to a good starting point, that would be much appreciated.

Thanks

Jim

[jvangelder]

I could see making all of the parts you have shown on a straight 3 axis, however if your budget allows a 4th for atleast accurate indexing would be a great time saver.

As for metric vs imperial scews, you can use either, the software running the steppers / servo's are just end up using some form of pulse per rev/in/mm or step per rev/in/mm etc

As for specific HM46 components, i cannot help as im not familiar with that mill.


First off how much do you want to spend? how fast do you want to go? Are you intrested in off the shelf components that you have to wire / configure your self or do you want something such as a board ready to run servo's / steppers, the servos / steppers them selves, and whatever interface is needed to control them all ready to run?


Did you make the aluminum rotor and cyclic control you posted?

-Jacob

[RC Heli adict]

G'day Jacob,
The aluminium rotor head "complete with metal ball links", displayed in my post was a bought unit which cost only $290.00 - it is for 700 size helis. Have a look here: JustScale NZ - Excellence in RC Scale Helicopters

That head is top quality but unfortunately, is not true to scale for the heli I am building. The coloured images in my first post are what I hope to have made. I am currently looking for a suitable manufacturer to produce the heads for a reasonable price. So far, costs are around $1800 for one hub and 3 blade grips (no other parts) and around $1200/head if I buy 10 hubs and 30 grips (3 grips per hub). If I am going to pay that sort of money, I think converting my mill to CNC is well worth it. The radio controlled heli hobby is lacking in the scale rotor head department. There are some available for larger helis, but in the 1500dia rotor disc size, not much around that look like the real thing.

Have a look at the pic below - that is the mill I have:
I believe it is another 45/46 clone...
With regard to converting my mill, I was hoping to do it for around $2000. I could be way off...

I may need to review this amount as I get more details on the conversion. If costs look like being too far over my budget, I will simply buy a few parts to start with, then more later on until I have everything I need.... To start with, I will upgrade the screws to ball screws. I guess all I need is to confirm is the screw diameter and length then find a supplier.... Steppers or servo??? What is the best option - This is one of the areas that I know nothing about - except maybe for the servos - I use them in my helis
I really like the 3D milling head - not sure what it is called - the cutter can be moved around at just about any angle - This may be on my wish list for a while. There may not even be one available for my mill...
As I do not know what components are needed, a "shopping list" would be handy..... All I have at the moment, is the mill, and a spare computer...... That's a start....

Oh, one other thing, which would be the best for the Z axis movement - move the whole head on the dovetail column, or just the quill? The quill on my model has a bit of backlash in the up down mechanism....

Jim

[Tkamsker]

Hi
For the Most Parts you will need 4 Axels but it should be possible.
The Rotor head where i assume it has to be verry precise to be centric i am not direkt.
I ecpect when you have to flip parts for manufactoring precision is gone.
I do have 4 Axis miller ( heiz 400 t )
Probably you have to combine lathe then Mill and build an special clamp Tool for the head ..
I am right now roaming i might have time in 10 days to look at it it you remind me. You also need quite capable cam Software to do that.
Cu
Thomas

[LUCKY13]

I dont think anyone makes a bolt on CNC kit for this mill so you will have ot make the parts you need to do it. Look at the RF-45 builds in the Machine build tread section for idea's of how to do it & places to buy parts.



3D milling head, no you want find such a think. Well thats not exactly right but the ones that I know of that could work are major high dollar in price and not that accurate anyway. This doesnt mean you want be able to do 3D milling, because with right software you can ( I expect you where talking about 5 axis milling anyway).


Servo's - steppers, this is a question many people ask alot. ANymore either can be done with a stepper setup being cheaper, and a servo system being a little smoother and maybe a little more accurate. WIth steppers sizing the stepper right is key to having a system that will stay accurate. With servo's you can get by with smaller motors which help's in many ways, plus the system is much quiter.


ANymore I fell the DMM A/C servo kits are hard to beat. Price is very good, and performce & durability is even better. IMHO DC brushed servo's dont even compair to this system, and the DMM setup may even be cheaper.



I think you can convert you mill for around your budget ( very close anyway depending on ballscrews you buy), but CAD/CAM software,tooling and workholding will be another expeince you need to think about.


You can build the convertion parts you need on your manual mill, you will need a boring head to help with making end mount bearing holders, and maybe even ballscrew nut mounts.


When you buy ballscrews & nuts buy them with the machining already done. This means you will have to figure out the you mounting with your end bearings and motor mounts first so that you know what machining to get done. Places like HomeShopCNC & Keling come to mind for getting the ballscrews ordered with machining all ready done. ( unless you can a lathe you can use to machine them yourself).


Again you will find more info about the proccess by reading build threads on the forum. Any RF-45, IH clone, BF-46 build thread will teach you a ton about what your getting into. These build threads will mostly be in the "Benchtop Machines" section of the forum.


I would also plan for a forth axis. This will be beyound what it cost to convert the mill but it will make the parts you build much easier to achive. I think you could get by for a while with out it but it will take longer to build a part. Still by the time you get to where you are producing parts you will understand this need much better so it would be better to wait until you get to this point before worring about a forth axis ( just read and learn about it so yuo can plan it into your electronics cabinet build, plus software purchase choices.



Jess

[uli12us]

Your machine is very similiar to a optimum BF30, for this machine you can buy a complete CNC-partset. But this is rather expensive. it cost some 3200€ and you need also new spindles which are 1000€. But you own a mill and a lathe and you can make all your parts.
Except the mechanical parts you need a 4axis steppermotor driver and the motors.
CNC Machining that man has a good description, what you need for your project.
What you need as well is a good dividing head.

[HorridHenry]

I think if I was wanting to make these parts,I would be making them in aluminium casting.

You would still need a mold of them in wood but at the end of the day the wood molds can make numerous castings of the parts to sell on ebay or other?

[RCaffin]

Those are injection molded parts. Your chances of reliably and economically making them in a converted HM46 are rather low - some might say non-existent.

If you want a small CNC Mill/Lathe, have a look at the Adepts from Queensland. You would still need to add a rotary axis to the bed. I have one, and it is working hard.

Comment: there are those who like to build CNC machines, and there are those who like to use them to make things. There may not be a large overlap.

Cheers
Roger
Sydney

[uli12us]

Maybe he can cast his parts in the waxmelt procedure. He can make his Cast in parts he can assemble to the complete part. After that he makes the mold heats it up that the wax melts and then put the ally in.

And, with a manual machine, you can make nearly everything, what is possible with a modern CNC-Machine. But it lasts a very long time longer than otherwise.

[RCaffin]

Those are injection molded parts. Your chances of reliably and economically making them in a converted HM46 are rather low - some might say non-existent.

Actually, I had better point out that it is the model bits which were injection moulded. The original parts which he is trying to duplicate in miniature were likely machined in several parts in 5-axis CNC machines and assembled. Cost per real rotor head might be of the order of $50k. Making miniature accurate reproductions on a home hobby 3-axis machine is going to be hard!

Cheers