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rdhopkins
03-01-2007, 07:14 PM
I've been lurking on this site for ages now and got a lot out of it so it's time to give something back.

Last year, I discovered the plans for the JGRO machine here on CNC Zone and just had to start building it. Now, I don't get a lot of spare time, my 1 year old son tends to take it all up but after a couple of months I managed to get the machine working. It's not the best or sturdiest JGRO but it does the job.

The plan was to then use the JGRO to cut a few parts for itself, replacing the bits that I didn't cut too accurately by hand. The problem is that when I built the JGRO, the only pipes I found for the bearings were 25mm outside diameter and it turns out that these flexed much more than I thought possible. I tried adding some sides to the JGRO to support the pipes from the outside with some success, particularly if I tighten a big clamp to pull the sides together but Joe's CNC with it's supported pipes was looking more and more attractive!

So that's how I got started with Joe's CNC. I downloaded the DXF files and converted them to metric, scaling them slightly smaller along the way as I don't have room for a full size model in my garage. My model will be 90% the original size. Of course this meant adjusting all holes for motor mounts, spacing for aluminium angle, etc. The JGRO is doing an excellent job of cutting the parts out.

I'm a bit late starting this log as I've already cut out most of the parts and assembled the main components of the base, gantry and Z axis carriage but there's still a fair bit to go.

I'd like to say thanks to everyone on this site for providing so much useful information and free plans without which I wouldn't have got started on this new hobby.

joecnc2006
03-01-2007, 07:37 PM
Glad you were able to use the DWG files, Its looking very good so far, lookforward to seeing it together, and see a comparison to you previous machine.

Joe

rdhopkins
03-02-2007, 03:39 AM
Hi Joe,

Many thanks once again for providing the dwg files for your machine - you must have put in many hours designing the machine and it's very generous of you to allow others to share this.

I do have a question for you: Why are some of the parts made from plastic? For example, the bearing adjusters - why not just make these out of MDF? I must admit, I got carried away when cutting all the parts out and just went ahead and made them out of MDF. They seem sturdy enough so I'll probably just go ahead and use them.

Roy

joecnc2006
03-02-2007, 08:37 AM
Hi Joe,

Many thanks once again for providing the dwg files for your machine - you must have put in many hours designing the machine and it's very generous of you to allow others to share this.

I do have a question for you: Why are some of the parts made from plastic? For example, the bearing adjusters - why not just make these out of MDF? I must admit, I got carried away when cutting all the parts out and just went ahead and made them out of MDF. They seem sturdy enough so I'll probably just go ahead and use them.

Roy

you can go ahead and use MDF many have, but i used HDPE for durability reasons, especially on the router holder, bearing blocks (because of pressure from adjustment screws), and leadscrew bearings to avoid wear and movement.

joe

zoltan
03-02-2007, 09:51 AM
Hi,

Are you going to make public the metric files? Myself I did not succed to convert them maybe due to the fact that I have only sporadically access to SW (a friend is working with a company which owns one), so, I gave up.

Thank you,

Zoltan

joecnc2006
03-02-2007, 11:38 AM
Hi,

Are you going to make public the metric files? Myself I did not succed to convert them maybe due to the fact that I have only sporadically access to SW (a friend is working with a company which owns one), so, I gave up.

Thank you,

Zoltan

you can use any free cadd program and diminsion the DWG files in metric.

zoltan
03-02-2007, 02:12 PM
Ups...you are right. I never thought to a such simple solution...wow...the bad habit to complicate things...

Thank you,

Zoltan

rdhopkins
03-03-2007, 06:15 PM
I found that the problem with the conversion to metric wasn't just having metric dimensions in the drawings but the fact that MDF over here in England is sold in metric sizes, e.g. 12mm instead of 1/2 inch.

In fact it's harder than that - the first pieces I cut out that included slots for the thickness of MDF (gantry ribs), I just made sure the slots were exactly 12mm wide. It turns out that the MDF I bought was slightly thicker than this. In the end I found that the thickness of the MDF differed depending on where I bought it from. I ended up modifying each DWG file specifically for the MDF I was working with at the time.

Add to that the available sizes of pipe over here for the rails along with metric bolt sizes and there are a substantial number of modifications to make. My CAD skills aren't too great so it took me a while to make these changes. I also ended up having to bring out the plane on a couple of pieces I calculated incorrectly.

rdhopkins
03-05-2007, 06:37 AM
I managed to get a couple of hours in the garage at the weekend to work on my machine - it's starting to look like a CNC machine now!

I started by cutting the aluminium angle to length for the X axis bearing trucks. I wasn't too pleased with these at first as the aluminium I got from B&Q (UK hardware store) was much thinner and flimsier than the eBay stuff I used for the JGRO machine (it was also MUCH cheaper), but once it is supported by the grooves in the MDF it seems sturdy enough.

Next I cut the grooves in the top using my lathe to recess the bolt heads. See pic 1. This is not the sturdiest setup for the lathe especially when using that 10mm cutter but so long as I didn't try to take too much off in one pass it was OK.

I then added the bolts, spacers and bearings to each truck to complete them and attached them to the gantry and bearing block. I had been looking forward to this moment - I slid the gantry onto the base and, wow! This is so much sturdier than my JGRO! (Not that the JGRO cannot be rigid - my version could just do with some "adjustments"!). I stood on the base, grabbed the gantry and rocked, pulled and twisted but it was rock solid - and this with only about 30 seconds of setting up the bearings!

I can't wait to get back and work on the rest of it. I wish I had more time to play with...

joecnc2006
03-05-2007, 07:57 AM
It starting to look like a machine now :).

One note:
The gantry is on the base backwards, the side with the larger spacing on X-Axis torsion box and the double pipe rails needs to be on the left (as shown with red circle in picture) this allows for the difference in space of the X-Axis bearing slide housing, and the circle (as shown with yellow circle in the picture) will be offset to allow the realignment of the leadscrew back to the center of the lower gantry torsion box where the anti-backlash goes, just slide the gantry to the ends and look through the hole, these should line up perfect.

Joe

rdhopkins
03-05-2007, 09:06 AM
Hee, hee! You're absolutely right! I was in such haste to see it come together that I didn't even notice. It's back in two bits again now anyway (the car sleeps in the garage at night - I need to clear a new space for the completed machine) so I'll make sure I get it right when I put it together for real.

Well spotted Joe!