Workshop project, CNC router table

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MrJohn

77 posts

Master Geek

#174985 12-Jun-2015 19:12

Hi,
I have made a start on a CNC router table, it is about 2 metres long (X axis) and almost a metre wide (Y axis), I have not finalized the Z (vertical) axis.

The base is a MDF box, the X axis movement will be via two roller chains (ex garage door openers) driven by a geared down Fisher and Paykel washing machine motor operating in stepper mode. The Y axis will be screw and nut powered by another F&P motor. The Z axis will also be via screw and nut and a 'conventional' stepper motor.

For slides I am using skateboard bearings running on steel tracks. The gantry structure is rectangular hollow section steel.

This is my first experience of this sort of project and I do not know how well it will perform however I will be somewhat disheartened if it cannot at least cut out sign boards etc and if I am optimistic it may be able to do a bit of engraving , maybe even rather coarse scale circuit boards.

I will have a couple of different sized routers for the spindle drive and might try to build a better quality spindle depending on how successful the main structure proves to be.

Right now, I have the base box built, on casters and steel reinforced. The X slides are working well and the basic gantry frame is in place. I have made the 40:1 worm gear reduction for the X axis drive. Now I am trying to work out the best design for the 'Z' slide.

John

jpoc

1043 posts

Uber Geek

#1324207 13-Jun-2015 21:06

I am working on something similar using designs from the "build your own cnc" folks.

You can get their basic design book cheaply off amazon as a kindle book.

I'd advise getting it as a source of ideas.

I am aiming for something that will mill out shapes from sheets of 8'x4' marine ply.

As part of my bootstrap project, I have proxxon mf70 milling machine. It is limited on z-axis height and y axis travel and height. I am currently modding it for greater Z axis height and I am working up a design for greater y-axis travel. After that, I will add one of the CNC mods. That will give me a medium size CNC milling machine which will be a big help in making the parts for the full size CNC router.

I'm in Auckland if you are interested in a meetup to compare projects.

What is your intended use for the router?

I'm mostly interested in boats or wiki-house projects.

Disrespective

1925 posts

Uber Geek

#1324261 13-Jun-2015 22:25

Very interesting project, but without any prior knowledge I would have thought the x and y axis resolution would be too course for circuit board etching. What will each step of the motors give you for dimensional control? Chain tension would be important in keeping this accurate I would have thought, too.

richms

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#1324290 13-Jun-2015 23:26

Dave Jones has some samples in that video for the kit hes bought from inventables.

If I wasnt so behind in other stuff I would probably get one of those too. looks awesome.

Richard rich.ms

MrJohn

77 posts

Master Geek

#1324321 14-Jun-2015 08:36

Thanks for the comments.

I would have made this machine big enough to handle a full sheet of MDF, plywood etc but the available space in my worshop is limited.

In theory (which for various reasons will not be achieved in practice) the resolution is 0.037mm on the X axis, 0.013mm on the Y axis with the Z axis still to be determined.

I spend a lot of time at our local aviation museum and I am optimistic the machine will be useful for cutting the occasional pattern for the pieces we have to make. Circuit boards, maybe, time will tell.

Chain drive does indeed need careful attention to detail, I will have a chain on each side of the table joined by a shaft across so that both chains are driven and the gantry will be fixed to the two chains as a protection against gantry wracking. The long runs of chain will be supported their full length and will be sliding on HDPE strips.

SepticSceptic

2186 posts

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#1330474 24-Jun-2015 10:23

richms: Dave Jones has some samples in that video for the kit hes bought from inventables.

If I wasnt so behind in other stuff I would probably get one of those too. looks awesome.

Do you listen to his AmpHour Podcast ?

richms

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#1330488 24-Jun-2015 10:42

SepticSceptic:
richms: Dave Jones has some samples in that video for the kit hes bought from inventables.

If I wasnt so behind in other stuff I would probably get one of those too. looks awesome.

Do you listen to his AmpHour Podcast ?

Not really. Without a picture too I cant concentrate on talking, its like audiobooks. I keep having to rewind to rehear things I missed so it just frustrates.

I can watch still untitled etc just fine when its just people talking on camera. But without that then its just like a phonecall. in one ear, out the other. No comprehension at all.

Richard rich.ms

SepticSceptic

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#1330520 24-Jun-2015 11:26

richms:
SepticSceptic:
richms: Dave Jones has some samples in that video for the kit hes bought from inventables.

If I wasnt so behind in other stuff I would probably get one of those too. looks awesome.

Do you listen to his AmpHour Podcast ?

Not really. Without a picture too I cant concentrate on talking, its like audiobooks. I keep having to rewind to rehear things I missed so it just frustrates.

I can watch still untitled etc just fine when its just people talking on camera. But without that then its just like a phonecall. in one ear, out the other. No comprehension at all.

Fair enough. Audio Podcasts work well for me, being stuck in Auckland traffic ... not much else to do. Though in free-flow traffic I tend not to listen, as concentration is needed on the driving.

Will jot down notes if I hear something interesting enough to pursue later.