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

How did you get it so quick ?

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Originally Posted by EddyCurrent

How did you get it so quick ?

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Next day delivery as standard, can't fault their service...although I've not had a reply to my email yet.

This is how I'm going to have my fence for pouring the epoxy, I might put an extra cross channel near the front of the frame as an extra channel for self levelling.

Attachment 11405Attachment 11404

Depending on how good it flows I was thinking about either a central aqueduct (epoxyduct ?) or two, one at each end. Obviously two are more wastefull than one. You don't fancy using the draught excluded idea then for the fences then ?

I'm going to test on a miniature set of welded steel first using some steel offcuts. I'll weld up a practice piece first like this...

Attachment 11408

Just hope it doesn't use too much epoxy...

Additional epoxyduct added....

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Might try the draught excluder on the test piece....can see it being messy to get off after the epoxy sets?

Had a little play at lunch with the pillar drill and a bit of 60x60x5 RSA as I was thinking of making the dummy gantry base out of steel (plenty in the scrap bins at work cou"stock"gh) to cut up and mess with. I printed the hole pattern out on some paper and taped this to the bottom of the angle and centre punched the hole positions (high tech stuff this) prior to drilling them. Used a 6mm drill bit for a bit of clearance as the holes on the carriages are Tapped M5. Bolted the carriages to the angle and I reckon it should work OK and will save me spoiling a good bit of 10mm 6082 Ali plate.

I will get some draught excluder and try Eddie's moat method on the underside of the angle so as to get a level surface to mount the carriages on. I know for the sake of getting the rails parallel I don't need to do this but it means I can try the epoxy out to see how good it is and also try Eddie's foam moat idea at the same time :cool:

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I did a test pour today and it's looking good. The draught excluder worked fine but where two pieces butt up at corners it needs a bit of glue between as there was a slight leakage through the joint. I'll do a full report in my own thread after it has cured. Also I'm thinking that when the moat is removed the edges of the epoxy would look a lot better if a bead of liquid nails was run down, like you would with sealant, then run your finger along it to create a nice fillet that will set hard and can be painted over.
It looks like the epoxy did not penetrate into the foam, which was my biggest worry, and I think that's because the foam is waterproof.

That's excellent news! I look forward to seeing the results Eddy.

Splashed out on some transfer punches to transfer the hole patterns to the other piece of 60x60x5 angle. Will weld up the cross member next week...really want to spend more than 45 minutes on it at one time.

I'm selling off all my RC Helicopters so there's more room in the shed so I should be able to get out in it and do some work on the gantry soon I hope. Just have to man up and try cutting the ali plate and stop worrying about messing it up :cower:

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OK so the draught excluder is here now.

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Will have a play with the epoxy sometime soon. Will level the angle that I'll be using to space the x axis rails out with a little like the pictures below. This will let me play with the epoxy and get used to mixing and pouring it and also give me a nice level surface to mount the carriages to.

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The bridge between the two rails will be silicone sealant, all the foam will be stuck together and the MDF end boards will be no-nailed to the steel.

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I'm seriously thinking of welding two steel 100x50x4 sections in an L shape and getting the machine up and running that way. I'll use epoxy on the steel to level the Y axis rails so they're level.

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I hadn't realised your gantry was very similar design to mine, did you read the Kingcreaky build log ?.
If you use the 7mm hole in the wide tub (e.g. ice cream carton) idea for pouring it's very civilised and controllable, you won't have any problems.

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Originally Posted by EddyCurrent

I hadn't realised your gantry was very similar design to mine, did you read the Kingcreaky build log ?.

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Yes I remember reading Kingcreaky's build, I was just thinking that to get it going and to keep costs down I'd use what steel I have left (got to use it up somehow) and build the gantry out of that and level using epoxy as I'll have a bit left over from doing the x-axis rails. Then I'll either keep it as it is or...use the machine to cut parts for itself and build the proper gantry...

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If you use the 7mm hole in the wide tub (e.g. ice cream carton) idea for pouring it's very civilised and controllable, you won't have any problems.

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Definitely going to use that method, seems like a winner!

What Width is the machine to outsides of Steel.?

:beer:Very apt The Avatar. ..Clive

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Originally Posted by JAZZCNC

What Width is the machine to outsides of Steel.?

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Its 850 to the outside of the x axis beams (100x50) I think, not got the laptop fired up so can't check.

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Originally Posted by njhussey

Its 850 to the outside of the x axis beams (100x50) I think, not got the laptop fired up so can't check.

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Ok well sorry don't think I can help then.! . . . I've got one of these spare in pieces Attachment 11511 but I'm sure it's only 800mm wide thou I will Dig parts out tomorrow and check.!

Cheers for the offer Dean, I've just measured and it's 900mm wide to the outside of the end plates :frown:

I've just bought a load of (800) various size bzp metric socket cap head set screws, got a quote from the company that my firm uses and then did a Google and found these guys who seemed to be a good price...fasteners :: set screws socket allen key :: cap head metric bzp ::

Cut up some of the 100x50x4 rectangular section steel to make a temporary gantry and just placed it on the x axis rails to check I cut it to the correct length!

Apologies for the blurred photo, took it on my phone...

Attachment 11552

Close up of the steel...fresh off the bandsaw so still got swarf and cutting coolant.

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I'll hopefully weld up the two pieces tomorrow and drill the mounting holes for the 20mm carriages in the 200mm long bits. I'm thinking of bolting the L shaped gantry to the 200mm pieces and then once it's square I'll stitch weld them to keep them square. Going to epoxy the face of the gantry for the rails and also the bottom of the 200mm pieces so the carriages sit flush unless by some miracle the steel is perfectly flat...

Had a delivery of some cap head bolts last week, I know I'll need more and different sizes but this should get me going!

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Any recommendations on 'best' place to get bolts ?

I was going to use our local supplier Hereford Fasteners but they were over twice the price of fasteners :: set screws socket allen key :: cap head metric bzp ::

I was happy with the price so went with them. Delivery bumps it up a bit but I needed some F clamps and a few other bits so wasn't that bad!

I must be blind today, you already provided that link a few posts earlier :stupid:, I have also found a local supplier that seems quite reasonable so will compare prices later.

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Originally Posted by JAZZCNC

Ok well sorry don't think I can help then.! . . . I've got one of these spare in pieces Attachment 11511 but I'm sure it's only 800mm wide thou I will Dig parts out tomorrow and check.!

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Might be interested in the gantry Jazz if you're thinking of selling. What width did it actually turn out to be?

Well spent the 1/2 hr in lunch marking and drilling the holes for the X axis carriages in the 100x50 box section. Used the 6mm transfer punch and the 60x60 angle that I've already drilled as a template to mark the holes and then the pillar drill to drill them (obviously.)

I'll probably dummy mount the rails to get an idea of how it will fit together and then mark the L section gantry for drilling the holes and bolt them together for a play....a bit like this...

Attachment 11568

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Today's small advancement....wish I could have a few hours uninterrupted in the workshop to crack on! Anyway I only managed to mark out (wrongly :hopelessness: ...what is it, measure twice, cut/drill once??!!) the holes for the bottom section of the gantry and drill them and put the carriage mount pieces on the carriages. Marked out one carriage mount but ran out of time to centre punch and drill.

Attachment 11584
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Looking good Neil. You just have to keep chipping away at it.

In post #224 and #221 the Y ballscrew looks like it is some way off the Y axis, dropped down on some spacers. Would it instead fit under the Z stepper motor and attach directly to the trapezoidal shaped plate on the side of the Y axis (i.e. ballscrew on top of the gantry)?

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Originally Posted by routercnc

Looking good Neil. You just have to keep chipping away at it.

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Thank you, that's what I am doing, it's just frustrating!

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In post #224 and #221 the Y ballscrew looks like it is some way off the Y axis, dropped down on some spacers. Would it instead fit under the Z stepper motor and attach directly to the trapezoidal shaped plate on the side of the Y axis (i.e. ballscrew on top of the gantry)?

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Re-drawn the gantry as I realised that if sent vertical there was a nice shelf for the chips/dust to collect on. How about this way?

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This shows the Y axis ball nut holder attaching to the Z axis plate.

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Neil,
You've turned the gantry round !, I thought the idea was to have the ball screw at the back out of harms way ? I know this reversed way puts the ball nut nearer to the Z axis but it's been stated that in practice it makes little or no difference to have it at the back.
I like the box section idea between the bearing blocks and gantry, it allows easy access for bolts and does not require counter boring.
Seeing as you have spacers between the frame and ball screw bearings on the long axis, why not extend them up so that the ball screw is more in the same horizontal plane as the rails ? I had them like your drawing at first but decided to raise them as far as possible. I'm thinking a limit switch could also be mounted on the extended spacer, above the ball screw bearing.

Don't forget my machine will be mounted at 75° from horizontal (eventually!) so before the gantry would have collected all the crap being thrown up by the cutter. This is only going to be a temporary gantry (famous last words!) as I'll use it to cut the aluminium parts for the "proper" gantry from the 800x1000x20 sheet of Ali I have lying around gathering dust, which will then be enclosed to protect the ball screw.

I've put the ball screws there to protect them from flying crap as much as possible from the cutter as they are hidden behind the rails where they are. They are only 45mm below the X axis carriages so I'm not sure that it would make any real noticeable difference in terms of performance?

Yesterday I set one rail parallel to the steel beam and bolted the steel to the carriage mounts to check that the gantry beam had the holes in the right place.

Attachment 11613

I had to drill some new holes as in my rush on Thursday I drilled the pattern 90 degrees out (less haste more speed!) Managed to loosely bolt the gantry in place but ran out of time so had to unbolt it all again. Need to get a shift on as now only got the workshop facilities for another month...

How do you plan to get the gantry at exactly right angles to the rails ?

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Originally Posted by EddyCurrent

How do you plan to get the gantry at exactly right angles to the rails ?

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I am going to clamp a piece of Aluminium sheet to the gantry back and use a large engineers square off the reference rail (bolted down) to square it.

The reference rail will be parallel to one 100x50 x axis rail so I might get a DTI and reference the 100x50 rail carriage off the rail side and then bolt that down firmly (threadlock) to the carriages before referencing the gantry.

I think I'm going to use a combination. What you said plus a digital angle finder plus a 3-4-5 triangulation measurement.
If they all arrive at the same point, great, if not, I'll do it again, have a rethink or maybe take an average reading.

How about setting it up as accurately as possible by measurement, then cut two right-angles in a piece of panel material - one cut across the bed to give a straight edge, then one cut along X at mid point of gantry to divide it in two. Flip over one piece on to the other and the difference between the two "right angles" is twice the gantry alignment error. I was thinking this one through the other day as part of my "how would I set it up accurately?" musings but not sure how it would work. I was also wondering how and where I would build in the necessary adjustment for correction.

Neale,
That's how I would set an engineers square up, by flipping it over as you say but in this case I'm on about bolting the gantry cross member to the two carriages each side sitting on the long rails with the adjustment being in the bolts fastening that cross member to the carriages. So it's bolting three pieces together and ending up with the cross member at right angles to the long rails.

I might just put the gantry piece on a flat table and bolt the carriage pieces at 90 degrees to that and then bolt to the carriages and see how the rail spacing is on the x axis box section. I'm not going to worry too much at the moment as I need to get the bulk of it built whilst I still have access to my works workshop and all the facilities there, only got 5 weeks left...

I've given squaring up the y to the x axis a little thought as well. I've seen Jonathan mention using dowel pins and long calipers but I was thinking a good first pass would be to fit a pen in place of the router and get the machine to draw a large square or rectangle. Measured corner to corner the two measurements should be the same if the gantry is square. This is how I square pieces up when working wood, it's pretty easy to get a good level of accuracy and it costs nothing.

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Originally Posted by njhussey

. . . whilst I still have access to my works workshop and all the facilities there, only got 5 weeks left...

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Neil, What's happening with the workshop ?

Works will still be there, however I shan't...

How's progress ?