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2.x Laser Cut 4x8 CNC Router

PostPosted: Sat Apr 02, 2011 10:09 pm
by dirktheeng
I am a nerdy engineer who has all kinds of ideas and gets as much fun out of designing stuff as actually building it (probably more). I want both a laser and a CNC router I really like the new 2.x laser that bart is making available via kit parts. I also really like the design of the blacktoe cnc router, but don't particularly care for the linear rail system and also think that there could be some improvements in weight and strength over what the designer came up with. So I thought, why not buy/build a 2.x laser and see what I can come up with to make the cnc router with the 2.x laser. I think I have come up with a good design consisting of parts that can be cut out with the 2.x laser. There are a lot of parts as the laser bed width is 20", but it is an accurate, presice robot and most of the parts are identical, so a proper setup could really make it quick and easy to cut out the parts. Further, the precision of the instrument makes it easy to make mating parts align and modern glues are often stronger than the materials that they glue, so maintaining accuracy and strength in "scabbed" together parts should be easy, but repetative. However, am willing and patient enough to do what needs to be done to put together a solid cnc router and I think it would be fun. I wanted to share the design and put it out for comment and suggestion. I will be posting my progress and am very open to suggestions and constructive criticism. :D

Re: 2.x Laser Cut 4x8 CNC Router

PostPosted: Sat Apr 02, 2011 10:38 pm
by dirktheeng
The start to any solid machine is it's base. I chose to use a tortion box because I can make it easily with the 2.x laser and because it is extremely strong.

The box is constructed of 1/4" plywood which can be cut on the laser and glued up. The skins are 3/4" plywood and the botom skin was sized to be 4x8 so a single sheet could work as it is the most important surface to maintain rigidity becuase it is in tension. I incorporated a mounting structure into the box elements for the linear guides. With the precision of the 2.x laser, it should be possible to alingn the parts within a few hundredths of an inch. Furhter, the design allows for the rails to be shimmed so they can be adjusted.

Here is a view of the complete tortion box with linear guids attached.

Here is a top view of the box structure without the skins and rails.

Here is the front view.

Right Side view.

Re: 2.x Laser Cut 4x8 CNC Router

PostPosted: Sat Apr 02, 2011 11:37 pm
by dirktheeng
None of the parts are bigger than the 2.x laser bed (except the skins which can easily be cut with a simple circular saw and guide rail).

Here are drawings for the rails in the x axis direction (the y axis is the long axis). Each x axis box beam consists of 11 cut parts, but there are only 4 unique parts.

Here is a view of the an assembled x axis box beam
X Axis TB Beam.jpg

Dimensioned drawing of the beam end member:
x axis endmember.jpg

Dimensioned drawing of the mid beam member:
x axis mid member.jpg

Dimensioned drawing of the x axis end cap:
x axis end cap.jpg

Dimensioned drawing fo the x axis scabb plate:
x axis scabb.jpg

There are a few things to note here. The end member has a square hole cut in it with a channel that goes to the outside. This is for a bolt to go through so that one can attache the extrueded aluminum guide rail. The end cap goes on either side and does not have the channel. This forms a box to retain the bolt. The strucural members are held together by scabb plates. The plates and the members have 1/16" holes in them which are aligned so that 1/16" pins can be used during glue up to maintain alignment. Further, the sizes were chosen to give maximum beam hight while maintaining the ability to cut two or four peices from each 12x20 bed peice.

There are 16 x beams needed for the box, so there are 176 pieces that need to be cut and glued together to complete the x axis beams. It won't take long to cut the pieces (maybe an afternoon). I'll do that while watching the wood woorking shows on PBS on a saturday. Glue up shouldn't take too long either.

Re: 2.x Laser Cut 4x8 CNC Router

PostPosted: Sun Apr 03, 2011 1:38 am
by dirktheeng
The Y axis box beams are constructed with the same techniques as the x axis beams. There are 16 parts to each y axis beam, but only 4 unique parts. There are actually 2 unique beams, one has a short scabb plates on one side the other has the same on both sides. The beam with short scabbs needs them to fit around the scabbs on the x axis beam. Again the pins assure alignment and the scabbs assure strength.

Here's a side view of the y axis box beam assembled:
Y Axis TB Beam.jpg

Dimensioned drawing of the y axis end member:
y axis end member.jpg

Dimensioned drawing fo the y axis mid member:
y axis mid member.jpg

Dimensioned drawing of the normal scabb plate:
y axis scabb.jpg

Dimensioned drawing fo the y axis short scabb plate:
y axis short scabb.jpg

There are 8 yaxis plates with 16 pieces each, so 128 total cut outs. Again, sized to get at least 2 and 4 pieces per 12x20 blank. There are then 304 total cut outs from 1/4" ply wood. It should only take a few hours to cut out all the parts.

The next thing to do is model the gantry. I have some rough sketches and mental images, so it shouldn't take too long to get it drawn up in inventor. I'll work on that as I have time tomorrow and during this week. Hopefully I will be able to update agian this week. Please comment if to care to.

Re: 2.x Laser Cut 4x8 CNC Router

PostPosted: Sun Apr 03, 2011 11:38 am
by twehr
Just a quick note on your cutting plans. You mentioned the 12 x 20 platform of the 2.x. I just completed my 2.x build and am finding that the actual cut/working area of the table is 11 x 21.45. So, if you planning requires the full 12" of the Y axis, you may need to adjust a bit.

Re: 2.x Laser Cut 4x8 CNC Router

PostPosted: Sun Apr 03, 2011 6:40 pm
by dirktheeng
That's good to know... that actually buys me some space to work with. I want to change up the way that I am attaching parts to make it easier to build. I'll work on it this afternoon and hopefully post something tonight.

Re: 2.x Laser Cut 4x8 CNC Router

PostPosted: Sat Apr 09, 2011 7:07 pm
by dirktheeng
I had a much busier week this week than I thought I would. I was on travel for work and did not have much of any down time. However, I did work on a modification that should make it much easier to assemble and maintain accuracy. I switched to a "dove tail" puzzle piece connection. I'm not going to post all the design drawings unless somebody asks, but I will show how this works and fits.

Here's an example of the joint. Instead of having to rely on pins for alignment, the pieces naturally allign by their joint shape.


To add strength, you can overlap the joints with a simple scabb plate and use a pin nailer to keep them in place as the glue dries. Very quick and easy.