[Biggs427]

I leveld the X tonight.

Build the dam and bridge hen applied painter green tape to prevent epoxy from sticking to the dam.

I heated the base to help the flow of epoxy.
Attachment 348800

I calculated the volume needed for a 4mm coat and added 10% more to compensate for the epoxy soaking in the wood. (This is completely non scientific!)

I used the heat gun on low fan speed mode to pop the few bubble that were forming on top.
Attachment 348802

Will see tomorow if I did a good job!

[Biggs427]

Was busy at work so the CNC building had to be postponed a bit.

The epoxy batch I mixed was not mixed enough so the eopxy didn't cure correctly. I removed all of it with my heat gun.

I proceeded to make a new batch. This time I didn't bother to make a form to save a little bit of epoxy; I made a form to level the full width. Still used two bridges.

The batch was good this time.

I waited a couple of days then proceed to drill holes using a jig I machined on my old CNC.


With the holes done, I proceeded to tap everything with M4 thread.


I aligned one rail with my straight edge then roughly adjusted the other with the first one a reference.


I tested with ballscrew block for any interferences and there's none.



Next step is to micro-adjust the rails spacing with a dial indicator to make certain that there is no binding.

[Biggs427]

I've started to build the gantry yesterday. Didn't do much, only the uprights.

First I machined the 6 uprights in 3/4 BB plywood. Three for each side.


Having a CNC, even a crappy one, comes in handy to do this kind of stuff.

With the uprights machined I had to sand a bit since I only had an upcut cutter. I made an error in Fusion and choose the wrong cutter. I figured it were faster just to sand the corners than redo the program.

Then I glued the parts together.


During the weekend I hope to have time to do the X axis truck attachment and assemble it to the uprights.

[Biggs427]

I started the X Axis trucks today.

I machined the parts on my old CNC. I definitely need a better dust collection for the next CNC...


I used a straighcutter for these parts so there was less sanding to do.

Now time to glue the parts together.


I had a specialist checking the ballscrew attachment. Seems I did a good job!


My original design had no brace but I decided to put one since I had the space without compromising access to the bolts holes.


Next step is to attach the uprights to the gantry beam.

[Biggs427]

I proceeded to install the gantry beam this weekend.

I even had a little help to wet out the uprights!


We aligned the beam then fixed it in place.


Even for a 24 inches span, I have the feeling that the beam torsion box might be a weak link. It is 4 inches thick but I still have room behind it so I might end up laminating another 2-3 inches of BB behind it. I have a plate of 3 3/4 BB ply laminated from a previous job; I thing that will help.

[fretman_2]

Mine's a torsion box beam made out of MDF and that's not the weak link...my gantry sides are. Your's are buttressed though so you ought to be good.

[Biggs427]

Thanks fretman_2.

A couple more steps were done yesterday.

I machined a 1/2 B plate to have a plane surface in front of the gantry. The holes machined aligned perfectly with the profile rails and the ballscrew blocks.


I glued it in front of the gantry.


While the glue dried I put 13mm M6 threaded inserts for the ballscrew blocks. I tested all sort of options and a hole with diameter 1mm bigger and thickened epoxy is what gives the best holding capacity. Better in fact than the laminated aluminium bar I used on the x-axis rails.


With the blocks inserts in place, I built a dam under the gantry to level the place it connects to the x-axis trucks. I used thickened epoxy to seal holes and prevent dripping.


With the dam sealed, I mixed a batch with slow hardener and poured it in. Removed bubbles with my heat gun and this morning, the epoxy was hard enough for me to remove the painters tape. Even if the epoxy was in contact with the glued surface of the tape, it was easy to remove. In fact, it was easier than the non-glued surface.


Next step is to self-level the face of the gantry where the Y axis rails will attach.

[Biggs427]

Now that I have a flat surface at the base of the gantry, I built the dam for the face of the gantry where the Y axis rails will attach. I left waxed screws in the holes to prevent epoxy from dripping in them. I used the holes as pilot holes for the bigger drill bit used to drill for the threaded inserts.


I made sure the Gantry base was perfectly leveled vertically before I poured the epoxy.

One day later, the epoxy cured and I drilled the holes where I put the inserts. 6.35mm for M4 inserts and 8.80mm for M6 inserts. I counter bored the holes a bit. That helped the inserts to stay straight when I insert them.

Using the same technique as before I epoxied the inserts in the gantry and made certain that all inserts were inserted 1mm below the surface of the gantry to prevent any interference.


I try to take my time at each steps; I have more time invested in this unfinished gantry than in my entire first CNC .

[Biggs427]

Installed the Y axis rails on the gantry yesterday. Took nearly two hours to adjust the spacing but seems that I got it right. +/- 0.001 difference; I think it is ok. The quality is crappy but here's a video I took.


I don't know how I could have been more precise. It is really hard to have a good reading with the caliper. So I attached the dial indicator magnetic base a truck on the lower rail and applied the indicator against the upper rail. Then I repeated the same with the indicator attached to a truck on the upper rail. Same reading. I think the gantry is straight.

I applied a small epoxy coat on the gantry for protection and maybe it could help with humidity changes between seasons.
Attachment 351242

[JerryBurks]

That looks like very capable and sturdy machine coming together. I wish I had used these linear profile bearings on my BigBamboo machine instead of the round rails. I am on the fence on upgrading but hard to take the machine out of commission and rebuild for several weeks.

[pippin88]

That looks like very capable and sturdy machine coming together. I wish I had used these linear profile bearings on my BigBamboo machine instead of the round rails. I am on the fence on upgrading but hard to take the machine out of commission and rebuild for several weeks.

Build an entirely new machine and then you'll have two!

[fretman_2]

LOL...I like your reasoning!

[JerryBurks]

Build an entirely new machine and then you'll have two!

Yes that would be a great idea but the consequence would be that I need to buy a bigger house as well or at least get a separate shop. My garage is already crammed so that I can barely fit another screwdriver much less an entire CNC machine.

[Biggs427]

Thanks Jerry!

I'm back from vacation with the familly and it's time to attack the Z Axis.

Before I left for vacation I leveled the base with an old epoxy left from a counter top job I did two years ago. The result is really shinny! I'm not even certain that I want to paint the CNC anymore! LOL.


I machined the plate that will attach to the Y axis truck and hold the profile rails with two 3/4 BB panels that will be laminated with a 1/4 aluminium bar to provide taping material for the rails bolts.


Same goes for the spindle plate but without the aluminium bar.


I had help to test the truck plate on the gantry. I wouldn't be surprise that she ask Santa for a Sherline next Christmas!

[Biggs427]

It's been crazy at work so it was less than crazy in my build.

I assembled the spacers between the Z axis plate and the Y axis trucks and the stepper support.
Attachment 355018 Attachment 355020

Then I removed the gantry from the base and applied a paint coat on both. I used an appliance epoxy paint. First coat shown here:
Attachment 355022

Once the paint has cured I will assemble the gantry and the Z axis.

[ger21]

Nice work there.
And nice to see another wood build.

[Biggs427]

Thanks Gerry!

I knew that wood was not the first choice of material for a CNC router. But I also knew that the end result quality/usability are not entirely related to material but in the design, planning and execution for a project like this.

[Biggs427]

I continue my build but at a slower pace.

Now that most of the parts are painted, I fixed the gantry and leveled it. I also roughly squared it with X axis.
Attachment 355736

Tonight I should have time to flatten the Z axis plate using my old CNC.
Attachment 355738

This CNC is crap and flexes like it is made of toilet paper but if I take really shallow passes, it is surprisingly true!

Then I should have a three functional and relatively squared axis.

[Biggs427]

I flatten where the Y trucks will attach to the plate
Attachment 355852

Then flipped it positioned the plate and flatten the Z axis rails slot.
Attachment 355854

Now I got to wait for Z rails bolts to arrive by mail in order to attach it and continue.

During this time I'm going to work on limit switch and cable management.

Back when I build my current CNC I only had optical switch so I used it for my limit/home switch. Is there any benefit with a mechanical switch over optical?

[Biggs427]

Tonight I made good progress.

First I squared the Y axis with the X axis. I needed a 0.012 spacer betwen the upright and the X truck. It is a good thing that an aluminium beer can is 0.004 thick!


Then I installed the Z axis plate on the Y axis trucks. I also tested the Z leadscrew / stepper and the fit is good.


I finally installed installed the Y ballscrew with temporary M6 bolts as my order of M6 socket bolts hasn't arrived yet. With the ballscrew in place, I placed the stepper bracket on the gantry upright to mark where to drill to fix it on the gantry.


I measured backlash on the Y axis and there is none that my dial indicator can measure.

This thing is starting to looks more and more like a CNC router.