Comments sought on new build: A CNC Router for RC Gliders and Planes

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Originally Posted by njhussey

Ultimately it won't matter as I'll be doing the T slotted base thingy...but it's still annoying!

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Neil are you thinking to T-slot the bed on the machine using the spindle.? IF so then you'll struggle because the spindle is far too fast for T-slot cutters.
Personally I find a matrix of tapped holes is far more versatile than T-slot and easy to do on the machine.

Sorry to see snapped tap.!! Done it my self so know how it feels.!:thumbdown:. . . Proper B@~~rd to get out. I just pecked away at it with pointy centre punch and kind of half destroyed it untill came came apart and loosened.

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Originally Posted by JAZZCNC

Neil are you thinking to T-slot the bed on the machine using the spindle.? IF so then you'll struggle because the spindle is far too fast for T-slot cutters.
Personally I find a matrix of tapped holes is far more versatile than T-slot and easy to do on the machine.

Sorry to see snapped tap.!! Done it my self so know how it feels.![emoji107]. . . Proper B@~~rd to get out. I just pecked away at it with pointy centre punch and kind of half destroyed it untill came came apart and loosened.

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No I'm cutting 16mm wide by 6mm deep horizontally and then putting 5mm flat strip over the top to create it....

The one thing I've found from playing with my router so far is that I need home switches as I can't consistently home to the same place if Mach is switched off or sometimes even if I load a different program...first job on the list after doing some plastic thrust bearings for an urgent breakdown job for Cadburys......

Been making chips today...plastic ones after surfacing the spoil board.

http://images.tapatalk-cdn.com/15/09...51bd48d0c1.jpg

Can't seem to get a good surface finish on a 1mm depth cut on the UHMWPE, can get a nice finish when going 2mm deep on cutting the I'D & ODs....using a single flute carbide cutter....needs more playing[emoji2]

One thing I'm happy with is the Z axis. I was expecting to have to loosen bolts on the Y & Z axis to adjust the spindle to get it at 90° to cut flat. I did a pocket with a 0.4 stepover and it was so smooth I reckon that by sheer bloody luck the spindle is almost exactly at 90°. When I surfaced the bed this morning (pocketing at 7000mm/min, 6mm 2 flute coated carbide bit at 0.4 stepover and 0.5mmdepth of cut) I couldn't notice any ridge at all, totally smooth.....jammy bugger, makes up for the broken tap in the base!

Sorry to hear about the tap! So annoying and as they are very brittle it's not easy to tell that they are about to go.

I've seen them spark eroded out, but it takes ages and I think is done underwater (?!).

I've had success with Jazz's method of pecking it out with hard tools and getting lucky until I could unscrew it. Sometimes there's enough sticking out to get a mole wrench on it, but not with yours.

If you definitely need the hole at that location and it won't budge then one option is to use the CNC machine to cut out a large through hole around the tap (say 30mm diameter) so that a nice round cylinder of aluminium is removed containing the tap. Then machine a round pocket (say 60mm diameter and 5mm deep) centred on the same hole. On the lathe turn up a part which fits the 60mm dia pocket and has a shank of ~30mm which goes right to the bottom of the hole -essentially a plug the same shape as the removed material. Drill a couple of countersunk holes (to keep the bolts flush) into the top flange of the plug, and through into the bed. Tap the bed and bolt the plug in place. Then drill and tap the centre hole again with a new tap!

Another option if you manage to get the tap out but damage the thread too much is to use a heli-coil which uses as oversized tapped hole to insert a spring shaped piece of metal which then creates the original thread diameter again.

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Originally Posted by routercnc

Sorry to hear about the tap! So annoying and as they are very brittle it's not easy to tell that they are about to go.

I've seen them spark eroded out, but it takes ages and I think is done underwater (?!).

I've had success with Jazz's method of pecking it out with hard tools and getting lucky until I could unscrew it. Sometimes there's enough sticking out to get a mole wrench on it, but not with yours.

If you definitely need the hole at that location and it won't budge then one option is to use the CNC machine to cut out a large through hole around the tap (say 30mm diameter) so that a nice round cylinder of aluminium is removed containing the tap. Then machine a round pocket (say 60mm diameter and 5mm deep) centred on the same hole. On the lathe turn up a part which fits the 60mm dia pocket and has a shank of ~30mm which goes right to the bottom of the hole -essentially a plug the same shape as the removed material. Drill a couple of countersunk holes (to keep the bolts flush) into the top flange of the plug, and through into the bed. Tap the bed and bolt the plug in place. Then drill and tap the centre hole again with a new tap!

Another option if you manage to get the tap out but damage the thread too much is to use a heli-coil which uses as oversized tapped hole to insert a spring shaped piece of metal which then creates the original thread diameter again.

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Cheers Barry, im favouring trying the smash it out with a hard pointed punch. The annoying thing was that I was backing the tap out the hole...

I like the plug idea, ive got to surface the Ali base at some point so might turn a press fit plug.

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Originally Posted by njhussey

One thing I'm happy with is the Z axis. I was expecting to have to loosen bolts on the Y & Z axis to adjust the spindle to get it at 90° to cut flat. I did a pocket with a 0.4 stepover and it was so smooth I reckon that by sheer bloody luck the spindle is almost exactly at 90°. When I surfaced the bed this morning (pocketing at 7000mm/min, 6mm 2 flute coated carbide bit at 0.4mm stepover and 0.5mmdepth of cut) I couldn't notice any ridge at all, totally smooth.....jammy bugger, makes up for the broken tap in the base!

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Why such a small step over neil.? . . . . With 0.4mm it must have took for ever.?

The Acid test for tram is when you use a wide cutter.!! Try 50mm with 75% step over and see what happens.? 6mm with only 0.4mm step over will hide most error. Also cut both X & Y direction.

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Originally Posted by JAZZCNC

Why such a small step over neil.? . . . . With 0.4mm it must have took for ever.?

The Acid test for tram is when you use a wide cutter.!! Try 50mm with 75% step over and see what happens.? 6mm with only 0.4mm step over will hide most error. Also cut both X & Y direction.

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The step over was what was in Cambam and gave a good finish so I kept it, yes took a while to surface it. I'm going to get a small fly cutter to do the surfacing in the future so we'll see then!

Going to be spending the next few weeks playing with speeds and feeds on various different materials...looking forward to it [emoji3]

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Originally Posted by njhussey

I'm going to get a small fly cutter to do the surfacing in the future so we'll see then!

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Wide cutter will give you perfect finish if trammed correct and take fraction of the time.

Wouldn't get a fly cutter these spindles don't like them. Get one of these with indexed tips http://www.wealdentool.com/acatalog/...nning_928.html

Or if on budget one of these. http://www.wealdentool.com/acatalog/..._Wing_250.html

I have the budget one above and it works well I can do my bed in a few minutes

Ok cheers guys, ill get one of those cutters, as work is paying probably the more expensive one.

What sort of step over do you guys use?

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Originally Posted by njhussey

What sort of step over do you guys use?

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Depending on material and Depth between 50-100% often 75%.

Well due to my hat at work changing from engineer to Web designer ive not done anything mechanical or electrical to the machine...However I have been cutting bits for an RC Glider in my lunches....

http://images.tapatalk-cdn.com/15/10...9d74055bbe.jpg

Now to crack on with CAD and finish off some drawings so I can make more models! [emoji2]

how are those parts cut ?

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Originally Posted by Blackrat

how are those parts cut ?

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Which bits? The wing ribs are nested so I can fit them on a 400mm x 100mm sheet (small packet post sixe) and ive got holding tabs on them to keep them in the sheet. The ply pieces are done the sane making sure the grain is in the right direction. The fuselage sides are done in 2 pieces and I cut them in half with a spline line so they can again fit in the packet for a small parcel and then fit perfectly together again and make a side. The balsa ribs and fuz sides were done with a 1mm cutter and the ply with a 2mm.....think that's about it.

Quick question to those who cut balsa (and lite ply)....I use these cutters...http://www.shop-apt.co.uk/single-1-f...us-metals.html

Which cut it OK, however they do lift the balsa and on soft balsa tend to rip it when cutting across the grain. What cutters do you use? I was thinking of trying some down cutters but was wondering if there were better ones out there?

Hi Neil,

I use 3mm 2 flute TCT router bits but have a similar problem on balsa. I also thought about down cutters but never tried it in the end and where possible I use lite ply instead and have larger cutouts to keep the weight down. Lite play tends to leave a thin layer of whiskers which is easily removed by running around with a scalpel to leave a clean finish.

Thanks

Thanks for that Barry, I prefer cutting lite ply as it cuts better, yes those little furry bits clean off on with a sharp craft knife. I'll have a play with different types of cutter and see which give the best cut.

Well been playing with the Router in work. Going to make small plastic (going to be Nylon) samples so I've been drawing them and cutting on the CNC router. Not getting the best finish on flat bottom pieces, looks like it's rubbing but ok on vertical sides. Using both single flute and 2 flute uncoated carbide cutters.

Attachment 16562Attachment 16563Attachment 16564

The same is true in Aluminium, sides are OK but the base is a bit rough. Used WD40 and air on the Ali, just Air on the plastic.

Attachment 16565Attachment 16566

I've just downloaded the 30 day trial of HSM Advisor and as if by luck on the plastic I was using 14000 RPM and a feed of 1950mm/min which is not a million miles off what they are suggesting (1790mm/min) so clearly needs some playing with to get the best results....

Need to make dust/chip extraction as the stuff is being flung bloody everywhere......need to finish off the machine/control cabinet....need to make the vertical stand for it as kneeling down is a pain (literally) and leaning over the machine is also a pain......just need another 6 hours in the day to do this!!!!!

Looking good Neil its great when you start making bits for real:cheerful:

Cheers Clive, been making lots of RC kits that I'm selling on eBay and now making bits for work. Had the idea this morning, drew it and made it by lunch....snapped 2 4mm cutters with a school boy error in not thinking about cutter clearances but apart from that all good. Pleased the boss anyway!

Below are some RC bits I'm doing for me...

http://images.tapatalk-cdn.com/15/11...80af3b0eea.jpg

http://images.tapatalk-cdn.com/15/11...b70a14c060.jpg

Hi Neil,

Nice work there. Often thought about selling kits on ebay but never got round to it!

With regard to your earlier post - the bottom finish on aluminium pockets is never perfectly smooth to the eye. I think your photos look OK but hard to tell with the light reflections. Can you feel ridges with your fingernail?

Here are my pockets which I'm pleased with - on a machine which is less stiff than yours:
Attachment 16567

Hi Barry,

I'm drawing up a few more planes at the moment, a 3 CH old timer and a low wing Acrobat. The top one in the picture is based on the ugly stick and I'll eventually have that on eBay but want to build and fly it first!

The bottom of the pocket is rough, not ridged but rough as if its been either tearing or rubbing it...I think it's just a case of getting the speed and feed correct. That's the first bit of ali cut on the machine so long way to go yet!

Do you remember the planes with the mighty midget motor and the unitone tx with the xfg1 triode(I think) valve in the rx with 4 wires:tickled_pink:

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Originally Posted by Clive S

Do you remember the planes with the mighty midget motor and the unitone tx with the xfg1 triode(I think) valve in the rx with 4 wires:tickled_pink:

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Showing the your age there Clive aren't you[emoji6].....bit before my time....Acoms Techniplus 2ch 27mhz was my first radio...with a Tamia Foed F150 Ranger car....

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Originally Posted by Clive S

Do you remember the planes with the mighty midget motor and the unitone tx with the xfg1 triode(I think) valve in the rx with 4 wires:tickled_pink:

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Can you say that again in English? A with what, for a with when ? [emoji23]

.Me

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Originally Posted by Lee Roberts

Can you say that again in English? A with what, for a with when ? [emoji23]

.Me

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See this http://myweb.tiscali.co.uk/norcimrad...ol/Radio17.htm and here is a bit more reading:- http://www.vintagercfiles.com/Grid_L...%20No%2010.pdf I am away at this time back Monday.

Mighty midget - forget all this low power electric nonsense - I remember all the fun I had with my ED BEE in a control line model (must have been around 1954/5. G.

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Originally Posted by GEOFFREY

Mighty midget - forget all this low power electric nonsense - I remember all the fun I had with my ED BEE in a control line model (must have been around 1954/5. G.

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Are you still going round in circles?:highly_amused:

Been machining some Nylon 6 for some sales samples for the USA and am getting fed up with the blinking chips going everywhere so thinking of making a dust shoe. I've got some 2" brush draught excluder so thinking of using that. Would a small airline in the shoe help clear the chips from round the cutter, would it interfere with the vacuum?

https://youtu.be/7yliULpNJx8

Ok, so I'm bored of cutting ply....so as I need to make a wire bending device to make undercarriages (I'll be doing carbon ones later...) I decided to try tickling steel on my machine.

http://images.tapatalk-cdn.com/15/12...21cbd1e0c0.jpg

Ok so it was 13000 rpm, 400mm/min feed rate, 100mm/min plunge, 0.4 stepover (0.75mm) 2mm 4 flute carbide coated cutter taking 0.25mm deep cuts.

Used a HSS 4 flute 2mm cutter first but that snapped...

Think I'll be playing with this some more [emoji106]

I've just bought the Estlcam software (through work) as I tried it last night and was impressed. It's much quicker than CamBam for doing RC bits (all I've tried at the moment...), I managed to do the CAM for 4 plates (600mm x 400mm) of nested parts in Estlcam last night in the time it normally takes me to do one in CamBam as it selects the geometry for you, if it's drawn correctly, instead of you having to join the lines into groups before you can select them and apply the CAM to them. CamBam also has the annoying habit of putting one random inside profile in an outside profile or viceversa.....I've just cut another plate for my Marabu plane and found one piece which has cut incorrectly like that. I normally spot them but on a couple of occasions I've missed them (rushing.....I know no excuse!) which means creating a new drawing for just that one piece....which is annoying :thumbdown:

I'm sure that I'll be using both bits of software but at the moment my preference for what I do is Estlcam, just thought I'd say!

Well, after all the recent custom jobs, my switch of hats from CNC operator/Machinist to Sales/Marketing & Web Design I'm back to the CNC building hat :yahoo:

I've already got the steel for the frame (it's sat rusting out in the yard) so decided to get the firm to purchase a new MIG welder, as my old second hand 90A stick welder was OK but I cant stick weld (not enough time spent practising really, not the welders fault as I'm sure it's just fine...) and today it arrived :eagerness: It is an R_Tech 180 Amp Portable Inverter MIG Welder so can be used for MMA and apparently even scratch TIG welding as well if I so feel inclined :cower: It has good reviews and I know Wobblycogs has one of their welders so looking forward to using it, even splashed out on a new auto darkening mask as mine has the head strap held together by gaffer tape :tongue:

Attachment 17616

Just in case anyone had forgotten what the frame is going to look like.....

Attachment 17615

So watch this space, frame design will be finished (got to figure how to mount the router to it) the workshop area tidied and cleared and then the frame cut up and welded. Going to add an air extraction system in the workshop for when I'm machining so that will be connected to the router enclosure to extract dust (balsa and ply dust) and at some stage a DIY dust/chip clyclone extraction system (and dust shoe for the spindle) to stop the plastic chips being flung round the enclosure.....lots planned, so little time to do it!!

Sweet Neil!

Knowing "how you roll" it sounds and looks exciting, i look forward to seeing how it goes down ;-).

Check out dubbleboost on YouTube as he's into his R-Tec stuff and so has a couple of reviews on the go.

The Mrs got me an auto darkening helmet for Christmas (asked what i wanted, I said "food, a decent meal for dinner will do me babe"), not tried it out yet but they seem to be quite ok for the price, has yours got a grind function too? I didn't think she new I was abit of a grinder...must have been watching from the house while I had the tunes on....

I'll show you mine, if you show me yours? Its got one of them spunky detail/graphics jobs on the outside, looks to nice to chuck about on the floor

.Me

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Originally Posted by Lee Roberts

Sweet Neil!

Knowing "how you roll" it sounds and looks exciting, i look forward to seeing how it goes down ;-).

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Knowing how I roll.....it'll be another 5 years till it's finished! [emoji15]

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Check out dubbleboost on YouTube as he's into his R-Tec stuff and so has a couple of reviews on the go.

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I've seen them, they're linked to on the R-Tech web site...they helped sway me (and the reviews) into buying it.

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The Mrs got me an auto darkening helmet for Christmas (asked what i wanted, I said "food, a decent meal for dinner will do me babe"), not tried it out yet but they seem to be quite ok for the price, has yours got a grind function too? I didn't think she new I was abit of a grinder...must have been watching from the house while I had the tunes on....

I'll show you mine, if you show me yours? Its got one of them spunky detail/graphics jobs on the outside, looks to nice to chuck about on the floor

.Me

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I got a plain R-Tech Speedmaster XL, nothing fancy...not opened the box yet but it's just a plain colour I think. Yes it's got a grind function....just checked :)

Attachment 17623

Had 20 mins before work this morning, drew up a motor mount and this morning cut it out using Trochoidal milling on my router...I wanted to use the "onion skin" method instead of holding tabs but my MDF bed is obviously not level!! The piece finished with the 2 finishing operations around the bosses and outside profile still to do! Still it gives me the opportunity to tweak the design a bit and re-cut it in lunchtime :D

There are 4 off 25mm long aluminium tubes (10mm OD, 6mm ID) to press in to the bosses for spacers which I'll then mill to the same height (should be OK as I did them on the lathe)

Anyway not bad for a first effort I think! Video will be up a bit later....internet connection is soooo slow today!

Attachment 18384

Attachment 18385

Video of machining the piece here.....no editing or anything fancy...just pressed pause a few times :whistle:

https://www.youtube.com/watch?v=cG70ZbJpfHs

Its always nice to see a part that has been designed and machined coming off. :applouse:

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Originally Posted by Clive S

Its always nice to see a part that has been designed and machined coming off. :applouse:

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Cheers Clive, not as shiny, smooth and polished as some but nevertheless satisfying [emoji1]