[mcentric]

So, I decided it was unavoidable. My initial plan was to write up my build log when construction was done, but I'm afraid I would just forget and leave out too much stuff. So here it is:

My idea was for a router capable of cutting guitar bodies and necks as well as some small to medium size wooden signs. As I have very limited space in my workshop (pic #1) I didn't want it any larger than absolutely necessary. Being the glutton for punishment that I am, I decided to design the router from scratch. That being said, there is nothing in this design that is in any way revolutionary, and almost all of it was either blatantly stolen or based on designs from this site. Time will show if I will regret this approach

After quite a few revisions I came up with the following design (pic #2). I knew right away that I wouldn't stick to it 100%, but the basic layout I consider finalized.
The following hardware was ordered/bought:
3Axis HobbyCNC Pro board with 305oz/in steppers
36V DC 9.7A 350W Regulated Switching Power Supply from Ebay
1000/750/300mm supported rails and bearing blocks from Ebay
3 meter TR12x3 Trapezoidal leadscrew and nuts from local supplier
Anti backlash nuts from Dumpster CNC
12/19/25mm MDF from local supplier
Assorted nuts, bolts and tools from local supplier

Comments and opinions appreciated.

Mikael

[mcentric]

The HCNCPRO kit came with excellent instructions and it went together very quickly (pic #1-4).
After looking around for a reasonable enclosure for the electronics, I realized I already had something that would work perfectly. My old Onkyo surround receiver that hadn't been used for about a decade was promptly gutted(pic #5-8), which also left me with a few useful parts like heat sinks and stand-offs for the HCNCPRO board. I'll make new front and back panels from sheet metal that I'll paint and pop-rivet on to the existing panels.


Mikael

[mcentric]

A carpenter buddy was nice enough to cut all my MDF to the desired widths which saved me a whole lot of time and headache. All that is left for me to do is to cut them to length with my manual miter saw.


Mikael

[mcentric]

First build day in the workshop:

Most of the day was spent cleaning up my workshop and putting old, unfinished projects out of the way (and hopefully out of mind ).

I decided to start on the gantry torsion box (pic #1 top drawing) as I think this will be the easiest one. Part of my concern was that I wouldn't be able to get the torsion boxes completely square. I am not a complete stranger to woodworking, but never with the precision required here. My concerns proved to be unfounded as everything came together remarkably well. The biggest challenge for me was to really take my time and triple and quadruple check my measurements before cutting (pic #2). The end pieces and internal braces were fastened with glue and staples and held in place with clamps (pic #3-4). The top and bottom skins will be screwed on with M6 hex bolts and cross dowel nuts. The front skin will hold two 750mm supported rails (pic #5) for the X axis (the long axis will be Y on this router). So prior to installing the front skin it was drilled and so-called M4 pronged tee nuts were installed on the back (pic #6). That's as far as I got today.


Mikael

[mcentric]

Second build day in the workshop:

Didn't get as many hours in today, but over all I'm pretty pleased with the progress.
I started where I left off yesterday and completed the gantry torsion box. The whole box is glued except for the top skin with the rails. I wanted to have the option to tweak this when I start aligning the axes. It was mounted to the torsion box with bolts and cross dowel nuts. I managed to get the rails to within 0.05mm of parallel, something that I was extremely pleased with (pic #1-3).

Next I started measuring and drilling the side boards of the table torsion box for the Y-axis rails. I pressed the M5 pronged tee nuts into the boards with my bench vice (pic #4-5), then test mounted the rails (pic #6).

My first major blunder came after I had mocked up the sides and ends of the table with staples. I cut the internal braces to length and test fit them. The fit was very good and in my excitement I glued and clamped all the braces in place (pic #7). What I had forgotten though was that the sides and ends were only temporarily mounted and not glued. I'll have to think it through and see what I do about it tomorrow. The table is in perfect square as it stands now so I really don't want to dismantle it. Might just try to pry the ends gently apart and squirt some glue in there...

That was all for today.

Mikael

[High Seas]

You could always -- not pull it apart (even a little).
Use glue blocks, say 1x1 inch (or 20x20 mm - whatever is convient) and re-enforce from inside the corners.
That way it will have a larger surface area for gluing and less likely to pull apart an already "square" setup.
Project is looking good!
Cheers - Jim

[mcentric]

You could always -- not pull it apart (even a little).
Use glue blocks, say 1x1 inch (or 20x20 mm - whatever is convient) and re-enforce from inside the corners.
That way it will have a larger surface area for gluing and less likely to pull apart an already "square" setup.
Project is looking good!
Cheers - Jim

Great tip Jim! Thanks
I love it when stupid mistakes have simple fixes. I'll install some blocks first thing tomorrow.

Mikael

[mcentric]

Third build day in the workshop:

A productive day I feel. The first thing I did was take Jim's advice and glue some support blocks in the corners (pic #1). This in addition to putting two wood screws in each corner seemed to work a treat.
I went over the frame and braces one last time to make sure no staples were left sticking out, that I had remembered to install all the tee nuts, and that the structure was still square. I then committed to gluing the skins on (pic #2-4).
The table end-plates/legs were next (pic #5-7). I made a real mess of one of the sides when I tried to tidy it up with the router. It's just cosmetic, but I know it will bug me. Once mounted I really got a feel for how heavy this thing is!! Hopefully the gantry will move smooth enough that my 305oz/in motors won't stall.
The last thing I had time to do today was mock up the torsion box that braces the gantry underneath the table and holds the Y axis anti backlash nut (pic #8).
Tomorrow it's back to work.... job that is But I think I made great headway this weekend and hopefully I'll be able to get things mounted on the rails in the next few days.

Mikael

[BobF]

How do you install the gantry?
Do you have to remove one of the ends?

[mcentric]

How do you install the gantry?
Do you have to remove one of the ends?

There is enough clearance between the end-boards and the rails to get one bearing block on at a time. Once i'm finished assembling the lower half of the gantry I will mount it to the blocks while on the rails.
Removing the end boards wouldn't be much trouble either as they are not glued, just fastened with bolts and tee nuts.

Mikael

[mcentric]

Build day 4.... kind of...

Haven't really had time to work on the proto-m this past week, but I managed to get in a few hours today.

The first thing I did was to continue working on the lower torsion box for the gantry assembly (pic# 1-2). Still a bit undecided about the way I mounted the Dumpster cnc anti backlash nut. I mounted it through the mdf brace because i wanted it absolutely centered in the torsion box. In doing that though I had to make the mounting hole large enough to fit the entire nut. This left only a few mm between the mounting hole and the flange screw holes. I fastened it with long wood screws and it feels quite solid. If it fails I'll just have to make a new center brace and mount the nut sticking out which will only require a 12-13mm hole in the brace. I'm only going to fasten the bottom skin with wood screws so that I have the option later on.
Four M6 pronged tee nuts were inserted in each side and will be used to fasten the lower halves of the gantry side boards.

The other thing I did today was test an idea I had for turning down the ends of of my 12mm trapezoidal leadscrews.
As I don't have access to a lathe, I decided to make my own... (pic# 3-4) I cut four 100x100mm blocks of 25mm MDF. In three of them I drilled a 12mm hole all the way through and then expanded the hole to 23mm half way through. Then I inserted a 12mm ID bearing in each block. In the last block I cut a 43mm hole, and then split the block in two. With 2 bolts and cross dowel nuts I could then mount my drill to the block. Using a 1000x100mm 25mm MDF board as a base I mounted the drill-block and one bearing-block to it with clamps. Voila! instant lathe I need to get a new file because my old cheapo one was all worn out. Still, I managed to turn the leadscrew test piece down a little over 2mm in about 4-5min. When I turn my 1250mm long Y leadscrew down I'll use all three bearing blocks for stability.

[ame="http://www.youtube.com/watch?v=ZTPdBKEO7vU"]YouTube - DIY lathe[/ame]

Mikael

[mcentric]

Build day 5 – a short one

I did a little measuring and prep work last night so that when I got home from work today I could get started on drilling the various holes for the lower half of the gantry side plates. The holes were drilled, but after that I had to re-drill all the holes .5mm larger because I could only get about half of the bolts entered into the tee nuts. I guess that's what I get for working with MDF and sub-par tools. But all in all I don't think it matters. It just gives me a little more to work with when I start fine tuning the axes.

I couldn't wait, so I just had to test mount the Y axis (pic # 1-3). Initially the movement felt very rough and stiff. I loosened all the bearing blocks and let them align themselves. Keeping in mind that this was merely a rough test fit, I attached a dial indicator to the gantry side boards and ran it the length of the table (pic # 4). One side showed a variance of +/-0.3mm and the other +/-0.2mm. I think that is a pretty good result before any fine tuning is done. By mistake I ran one of the bearing blocks off the end of the rail while under weight and one off the balls fell out. I couldn't feel any difference in the movement, but I'll try to push it back in place when I dismantle the the assembly tomorrow.

The last thing I did was mock up the gantry to get an idea of how the weight would affect the Y axis movement (pic # 5). The difference was negligible, which set my mind at ease that my 305oz/in motors will be up to the task. I was very pleased with how solid the movement felt. There was no play in the bearing blocks and no noticeable racking in the whole assembly.

[ame="http://www.youtube.com/watch?v=8DBgnb7HM9U"]YouTube - Proto M gantry test[/ame]

Mikael

[Vegabond]

Hello Mikael, your machine looks fine , have you build more than in post 12?


Robert.

[mcentric]

Hello Mikael, your machine looks fine , have you build more than in post 12?


Robert.

Thanks Robert I actually got quite a bit of work done today. Post will follow.

Mikael

[mcentric]

Build day 6

It's been a slow couple of weeks in the workshop but I got quite a bit of work done today. Well, build day 6 is actually more like build day 6, 7, and 8 but 90% of the work was done today.
The build has had a different feel today as, for the first real time in this build, I'm working completely without drawings. The Y axis carriage and the Z axis have been solely fuzzy images in my mind. The result has been a lot of trial and error, mostly in how to connect the different pieces together. Because my mind has been so completely focused on working out the design, the accuracy of my cuts and holes has suffered, leading to parts being scrapped and time wasted. Not something that's compatible with my already impatient nature. At the end of the day, though, I am pretty pleased with the outcome.

My original plan was for a simple box, with the front wall carrying the Y axis bearing blocks on one side and the Z axis rails on the other. It quickly, though not quickly enough apparently, became clear to me that I had an extreme conflict of mounting holes in the front wall. The solution turned out to be a big plus for the design in terms of rigidity. As the pictures show, I installed a double wall in the front of the box to carry, respectively, the bearing blocks and the Z rails.
My initial idea was to mount the side plates that can be seen in the drawing of post #1 for the purpose of rigidity. The way the carriage feels now though, I'm not so sure I'll need it, and it would certainly help on the rapidly growing weight of the whole gantry assembly.

I hope the pictures speak for themselves, but please ask questions or post comments/views. They would be greatly appreciated.

My next task will be to finish the gantry sides. Then I'll have to tackle another “gray area”... the motor mounts and lead screws.

Mikael

[mcentric]

Build day 8

I'm just skipping build day 7, as it was all about test fitting the gantry with mock-up sideboards. I didn't have time to write up a post about it yesterday, so I'm just going to skip to today.... which has been much more interesting

Much of the time I put in yesterday went into measuring and drawing the final design for the top half of the gantry sideboards. I wanted enough of a rearward offset of the gantry to maximize the workable table area and to center the weight of the X axis carriage and Z axis over the Y axis bearing blocks. So the first thing I did today was to cut them out and drill the various mounting holes (pic #1).

This thing has become so heavy I didn't even attempt to mount the gantry on my own. My lovely, pregnant, wife was kind enough to help me, and it came together a lot easier than I had hoped for. She has been very understanding in my current state of CNC madness, but I fear she thinks I have started snorting uncut MDF dust, and I feel an intervention looming

So, here it is (pic #2-3). The finished design except for the motor mounts, lead screw assembly and the electronics. The usable work surface turned out to be 77x57cm with 18cm in the Z. The beast weighs in the neighborhood of 90-100kg, I estimate, and feels rock solid in all three axes. After only about 5 minutes of tuning I got the machine running at within 0.35mm of square across the whole work surface. I'm very happy with that, and don't think I'm going to try to improve on it before I see the results of the first cuts.

This will be as far as I get before I go on summer holiday on Friday. I'll be back in about 2 weeks.

[ame="http://www.youtube.com/watch?v=YMi2SNgmo1I"]YouTube - Proto M finished design minus motors & lead screw[/ame]

Mikael

[wongster]

Hi Mikael,

That's a really nice job done!

Possible to show some pics of how you mount your lead/ballscrews and connect it to the moving gantry?

Regards,
Wongster

[mcentric]

Hi Mikael,

That's a really nice job done!

Possible to show some pics of how you mount your lead/ballscrews and connect it to the moving gantry?

Regards,
Wongster

Thank you Wongster

I'll post some pics of the leadscrew/motor mount assembly as soon as I get back from holiday in two weeks. It'll be the first thing I start working on.

Mikael

[wongster]

Thanks!!! Enjoy your holiday.

[mcentric]

Back from my vacation. I haven't gotten started on the leadscrews yet, but I just wanted to post a few pics of my almost completed controller box. I've yet to attach a connector for the home/limit cables. There is also plenty room for later additions of spindle relays etc.