1200mmX900mmX170mm 4axis cnc

Hello everyone.
This is Nick from Greece.
I am looking forward to build my own cnc and to avoid the most mistakes that will cost me money, time and mental brakdown!:gorilla:
Althought I am a member at other cnc forums,I choose to post here my attempt for some reasons that I will prefer not to analyse right now.
Sooo, I am planing to build a cnc with the dimensions I wrote above.Steel frame and bench, I am planing to combine welds and screws for the bench since my workshop is small and I will have to build the machine outside the workshop and disassembly it and reassembly it again in the working area, this will also be a one man build , so this way it will be a little bit better for me to relocate it.
The cnc will be used most for wood working, guitar building, etc and I will be pleased if it will be rigid and accurate enough so I can cut aluminum parts.

Caution My cad abilities are awful,lol, prepare your eyes!!!
CAd program I use is Rhino 4 and Vectric Aspire 4 for cam.

Thanks everyone for taking the time to read and special thanks to everyone that will participate to that attempt!!!

Yesterday at work I felt very lucky, since I thought I found my machin ,almost ready ,build for me!!!
But unfortunattely someone place an engine on and I lost my chance.:single_eye:
Attachment 21498Attachment 21499

Workbench plans.
50x50x3mm build, any suggestions?
Attachment 21500Attachment 21501Attachment 21502

Hi Nick,

I'm still learning, but some of the best bed frame designs I've seen have a bed which attaches to the legs with screws, so you can change the height of the bed, or swap it out for a different one in the future. The other thing I thought was quite sensible would be room at the front and sides for sliding large pieces in underneath to work on their edges - looks like you've hit the nail on head already for that one though!

Hope that helps!

Any thoughts about the design and the dimensions of the steel tube I use?

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Originally Posted by Nickhofen

Any thoughts about the design and the dimensions of the steel tube I use?

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I think 3mm is a bit thin for tapping into

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Originally Posted by AndyUK

Hi Nick,

I'm still learning, but some of the best bed frame designs I've seen have a bed which attaches to the legs with screws, so you can change the height of the bed, or swap it out for a different one in the future. The other thing I thought was quite sensible would be room at the front and sides for sliding large pieces in underneath to work on their edges - looks like you've hit the nail on head already for that one though!

Hope that helps!

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Hi Andy.
Somehow I miss your post earlier.
Thanks for the comments, I read other's guys threads here and I am stealing ideas, I hope this is not inappropriate. :-).
Something I forgot to mention is that at the one end of the bench ,that is at a lower lever is for the rotating axis.

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Originally Posted by Clive S

I think 3mm is a bit thin for tapping into

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Hi Clive.
Nice input,thanks!
I will then go for 50x50x4, maybe?

Nick.

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Originally Posted by Nickhofen

Hi Clive.
Nice input,thanks!
I will then go for 50x50x4, maybe?

Nick.

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Hi, May I ask what rails/tracks/guides you are using and what is the method of attachment? What do you want to cut?
The span of the section is where you need to pay attention. Mass/stiffness can be your friend.
Welding can be you enemy with shrinkage and distortion. The 50 x50 x3 might be used for bracing , but the main rail support might be stiffer with 75 X 50 X 5.0 RHS.
Tool load and weight of the material you are cutting will also dictate frame material properties. Sorry not many answers and a lot of questions.

Paul

Hi Paul, thanks for your participation to this thread.
Rails I am planing to use HIWI linear square rails, attached with screws .
I am planning to cut wood mainly and I will be glad if the machine can cut aluminum also,I know that I can not have a cnc that can do both works well, so the main purpose is to build a cnc foe woodworking-guitar building.
Thanks for the input about the main rails, i will use it at my upgrate workbench design.

I have a lot to learn....

Is there a reason not to go with that design on the bench?I mean the lower section for the 4 th axis? The bench will have a movable section at the one end that will cover the 4th axis and when is needed I will remove that part so I can machine big parts that are going to be heleded at the A axis.

Bump.....!!!!!

A guy near by me sells one of those as a kit, only the frame, are there any good ?
If I drop some Nema 23 ,3 or 4Nm.
http://www.cnc1.eu/en/KH1000GSKIT.htm
What a headache.

hi. I think your design will be much stronger than the one you have linked to.. There should be no problem with the removable section for your 4th axis as long as it lines up with the rest of the bed

Looking at that link, my first reaction is that the gantry sides are way too flimsy. They need some triangular bracing at least.

Ok guys, thanks for the reply, I wasn't sure anyone is watching this thread.
I will move forward with my build and abandon the idea to buy the chasis.

Advice needed.

I repost here since at my other thread I didn't get any respond.
I am thinking for something like that for my X axis, I prefer to build it bolt on ,with minimum welding, since it is one man job and better to handle, plus I want to avoid metal stress,that I am going to get with welding.
X axis is made from 90x90x900x4mm steel structural sections
At front and back of the steel tubes I will place two steel plates 5mm to stiffness the structure ,also the two plates ,left and right, are going to be 5 -7 mm.
Attachment 22439
Attachment 22440

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Originally Posted by Nickhofen

Advice needed.

I repost here since at my other thread I didn't get any respond.
I am thinking for something like that for my X axis, I prefer to build it bolt on ,with minimum welding, since it is one man job and better to handle, plus I want to avoid metal stress,that I am going to get with welding.
X axis is made from 90x90x900x4mm steel structural sections
At front and back of the steel tubes I will place two steel plates 5mm to stiffness the structure ,also the two plates ,left and right, are going to be 5 -7 mom.
Attachment 22439
Attachment 22440

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With 2 off 90x90 sections stacked on top of each other with what looks like another 90 mm gap the gantry is going to be very tall. This means the loads going into the top rail are along way from the X axis ballscrews (which react that load) and you are reliant on the sheet panel sides to do the load transfer.

Is this height because you need lots of Z travel?

Whilst yes this would work, I think there are more elegant steel fabricated solutions. For example this one from 'Toomast':
Attachment 22445

There's this one too:
Attachment 22446
Both involve welding so as you point out care is required during construction.

More popular is aluminium extrusion for the gantry because it is easier to work with:
Attachment 22447

For wood working, guitar making and occasional aluminium I would say all the above are suitable designs.

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Originally Posted by routercnc

Is this height because you need lots of Z travel?.

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Sorry I forgot to mention that the total height is 180mm.
I have read at another thread here , that to eliminate the forces when Z axis is cutting, the carriege must be at least at 250 mm from their outer sides.

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Originally Posted by Nickhofen

Sorry I forgot to mention that the total height is 280mm.
I have read at another thread here , that to eliminate the forces when Z axis is cutting, the carriege must be at least at 250 mm from their outer sides.

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Hello !
I think you (or me) has misunderstood..
The bearings on x axis your long axis should be wider preferably so that the tip of the cutter is between them when viewing the machine from the side.
The y axis bearings on gantry can be closer.

If you use 90x90x4 steel with no welding, how will you close the ends to be able to bolt there?

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Originally Posted by Nr1madman

Hello !
I think you (or me) has misunderstood..
The bearings on x axis your long axis should be wider preferably so that the tip of the cutter is between them when viewing the machine from the side.
The y axis bearings on gantry can be closer.

If you use 90x90x4 steel with no welding, how will you close the ends to be able to bolt there?

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How close can be the bearings on the gantry so I can have good accuracy and eliminate the tolerance when torgue applied on Z axis ?
The ends of the tubes is going to be welded with steel flanges, I prefer minimum welding for minimum stress and to be able to adjust- align everything.

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Originally Posted by Nickhofen

How close can be the bearings on the gantry so I can have good accuracy and eliminate the tolerance when torgue applied on Z axis ?
The ends of the tubes is going to be welded with steel flanges, I prefer minimum welding for minimum stress and to be able to adjust- align everything.

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Aah then I understand about the ends ;)

I don't know about the critical spacing of y axis bearings but I've seen lots of people using gantrys that are only 100mm high (50x100 steel tube) and that seems to work. The better question is what distans you are planning from lower y bearing to workpiece?

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Originally Posted by Nr1madman

Aah then I understand about the ends ;)

I don't know about the critical spacing of y axis bearings but I've seen lots of people using gantrys that are only 100mm high (50x100 steel tube) and that seems to work. The better question is what distans you are planning from lower y bearing to workpiece?

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200mm maximum, with rising table that will minimize the distance for aluminum cutting .

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Originally Posted by Nickhofen

Sorry I forgot to mention that the total height is 280mm.
I have read at another thread here , that to eliminate the forces when Z axis is cutting, the carriege must be at least at 250 mm from their outer sides.

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I fount another thread "http://www.mycncuk.com/threads/8975-Linear-rail-question?p=88244#post88244", one that you have start Robert (Nr1madman), where Jazzcnc states that 160mm for Y axis height is good enough!
Time to redesign !

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Originally Posted by Nickhofen

I fount another thread "http://www.mycncuk.com/threads/8975-Linear-rail-question?p=88244#post88244", one that you have start Robert (Nr1madman), where Jazzcnc states that 160mm for Y axis height is good enough!
Time to redesign !

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Hohoho you know the phrase "seek and you shall find". Well done ;)

But if I remember correctly my choice was 80x160 profile for gantry but jazz and Boyan stated that 2pcs of 80x40 is plenty enough in L formation. That gives the gantry a hight of 120mm!

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Originally Posted by Nr1madman

Hohoho you know the phrase "seek and you shall find". Well done ;)

But if I remember correctly my choice was 80x160 profile for gantry but jazz and Boyan stated that 2pcs of 80x40 is plenty enough in L formation. That gives the gantry a hight of 120mm!

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I think I have seen Jazz use 90 by 45 as that is the correct spacing for 20mm rails in profile

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Originally Posted by Clive S

I think I have seen Jazz use 90 by 45 as that is the correct spacing for 20mm rails in profile

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90x45 each tube Clive? And what spacing between for the screw can we say that is ideal?

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Originally Posted by Nickhofen

90x45 each tube Clive? And what spacing between for the screw can we say that is ideal?

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Not sure what you mean by this the two profile are fitted together to make an L so the lower one is horizontal with the other one sitting on top vertical, the BK and BF bearings for the screw will fit the slots in the profile

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Originally Posted by Clive S

Not sure what you mean by this the two profile are fitted together to make an L so the lower one is horizontal with the other one sitting on top vertical, the BK and BF bearings for the screw will fit the slots in the profile

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Thanks Clive, now I get it.

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Originally Posted by Clive S

Not sure what you mean by this the two profile are fitted together to make an L so the lower one is horizontal with the other one sitting on top vertical, the BK and BF bearings for the screw will fit the slots in the profile

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You are correct as always ;) but I think the smaller 80x40 was okay strength wise, just alot more handy with the 90x45 because of the bearings and the clever bolt on approach

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Originally Posted by Nr1madman

You are correct as always ;) but I think the smaller 80x40 was okay strength wise, just alot more handy with the 90x45 because of the bearings and the clever bolt on approach

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Exactly, better job all round the bolt holes are perfect for the 45x90

After some sleepless nights watching some video tutorials about Fusion 360 CliveS point me, thanks Clive, I came up with this.

The questions now are:
Can I use two pieces from this aluminum extrusion for the Y axis, not complete on the photo, and screw them them at left and right on the supports?
And what extrusions can I use for the X(long) axis, to support the Hiwin rails and screws.

http://www.ebay.co.uk/itm/like/17233...?ul_noapp=true

I was thinking the option of using aluminum extrusions for the axis, since this way there is no need for drilling ,tapping and leveling with epoxy!

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Can I use two pieces from this aluminum extrusion for the Y axis, not complete on the photo, and screw them them at left and right on the supports?

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Yes use two pieces one flat and one upright like an L. Then drill the upright one down the channel slot and bolt it to the flat one with tee nuts M6 90mm cap head

Thanks Clive, always so helpful!
Can I use the same extrusion for the x(long axis ) to bolt 20mm rails and ballscrew on? Or I need a thicker extrusion?

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Originally Posted by Nickhofen

Thanks Clive, always so helpful!
Can I use the same extrusion for the x(long axis ) to bolt 20mm rails and ballscrew on? Or I need a thicker extrusion?

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Its very nice using extrusion (heavy duty) because the slots it the 90x45 are exactly correct for the bk and bf bearings and can be mounted with tee nuts 6MM the 20mm rails will also mount into on top of the slots. You would have to work out how to fix the extrusion to your frame.

The ends of the extrusion can also be tapped without drilling for M12 bolts. with a spiral tap in an electric drill.

I see that they are not as cheap as steel tubing but that save me from a lot of work and time!
Thank you Sir!

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Originally Posted by Nickhofen

I see that they are not as cheap as steel tubing but that save me from a lot of work and time!
Thank you Sir!

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Yes if you decide on them get the company to cut them to length

I will message the seller,Thanks!
One more silly question..For X (long axe) what side is better the extrusion lay on the bed side, the sort(45) or the thick(90), for matter of stability.