[routalot]

Have you checked out the price of epoxy?It isn't the cheapest substance and some shrinks more on curing that others.

[AlexFComp]

Hello,

As I said yesterday, I have been working on a new design based on your suggestions and on what I could see on other forums these last two days .
I actually came up with two designs but only kept one.

I attached pictures of the first one that we will call V3.
As you can see here, I mounted both X-axis linear rails in a flat horizontal position instead of a vertical one like on the previous design. I then used 90° 3/4'' thick steel connection plates with stiffeners to connect them to the gantry side plates and the ball screws. The table frame was also modified.
In the end, I decided to dismiss this V3 design for multiple reasons:
- First, because of the gantry 90° 3/4'' thick connection plates and stiffeners. As shown on one of the pictures, I was loosing ~65mm of travel on both end of the Y-axis, so 130mm in total.
- Then, I didn't like how the linear rails were baring the gantry's load. It looked like a cantilever beam with a load applied on one end and I was afraid that this would end up wearing the linear bearings out too fast. I could have divided the gantry side plates into two plates and attached the upper portion in the center of the 3/4'' thick horizontal plate (right over the carriage) with an angle, while keeping the bottom portion connected to the ball screw nut housing (like a sort of step). But I thought that there was an easier way to get to a similar result.
- Finally, I also didn't like how the design was relying on the 90° plates to keep the whole gantry straight. At that thickness, laser cutting 3/4'' steel plates usually leaves you with a pretty rough cut. It wouldn't offer proper mating faces which means that I would need to get them properly surfaced and machined to get a good 90° angle.

So I came up with a mix of what I did in V3 and what I 3D modeled before. We will call it V4 (pictures attached as well).
- In this design, you can see that the linear rails are back on the sides of the table right next to the ball screws. I had to add shims to the linear rails' carriages to get them to the same level as the ball screws' nut housings. Yes, this increases a little the load applied to the bearings since we are a little farther from the rails, but I don't think that this is as bad as what I was getting with V3.
- I also beefed up the frame with 120x80mm extrusions on the sides for optimum stiffness, as well as some bracing under the table like some of you recommended.
- With this configuration, I only loose ~30mm of travel on both ends of the Y-axis, which I find acceptable. The final work envelope of the machine is now ~940mm x 790mm x 150mm. I am happy to say that I still managed to keep the full travel length of the X-axis ball screws, even after placing both of them on the sides.

I still have to think about a couple more details before pulling the trigger on ordering the aluminum extrusions though. Anyway, I am not in a rush either.

I also checked where the Center of Mass of the gantry + head is currently located. As you can see on one of the V4 pictures, it ends up between both linear bearings but much closer to the back one. Would that be an issue? Do you actually need to be exactly between both linear bearings? I still have a little bit of space left to bring it a little forward.

[machinedude]

looks like the legs are a lot better and the design you have now looks like a lot more of what you see the majority doing. i'm not in the majority but the guy paying the bills for the build has the final say every thing looks well placed at a glance. the closer you can keep the center line of you spindle to the gantry cross beam the better. keeps things more rigid. as long as you are over top of the bearing trucks when the spindle is down i would think you are ok. spacing is something that is important, to little is no good and to much is no good either. but what you have looks ok. this type of machine has deflection to some degree so it;s hard to get rid of it all. HSM advisor will tell you how much force you have while cutting i would expect things to fall between 25 to 50 pounds at the spindle. if you planning on doing a lot of 3D milling for mold making those kinds of tool paths don't usually have heavy loads to begin with but you can control the roughing quite a bit with modern tool paths to keep the loads down you just trade off time for material removal rates.

[ger21]

You need some triangle bracing on the side too. It'll wobble when the gantry starts and stops.

Also, is the spindle mounted to a single bearing? Two would be much stiffer. And I personally don't like to see the spindle hanging down that far.

[routalot]

The centre of mass issue is a sideshow.Once you are cutting the reaction force will be far greater than the mass of the gantry,simply because of leverage and the gantry height.

[AlexFComp]

You need some triangle bracing on the side too. It'll wobble when the gantry starts and stops.

Also, is the spindle mounted to a single bearing? Two would be much stiffer. And I personally don't like to see the spindle hanging down that far.

Yes, I will be using all 4 linear bearings instead of 2 for the spindle. I am also thinking about using two clamps to properly secure it.

Yesterday I received the first parts from BST Automation. Everything looks good and pretty straight.
I am still figuring out some details regarding the extrusions (mainly if I use brackets and gussets instead of the anchors). On a good note, I discovered that the Canadian company called Faztek that sells extrusions online is actually right accross the street from our workshop. Pretty convenient!

I'll send updates once I get more parts and start building.

[AlexFComp]

Hi !

Got some more parts in today. Basically, I assembled the frame. It seems pretty solid and I still haven't added the top steel plate that will be the table.
I decided to skip the epoxy/sand fill for now and see how it will do first.

Now, I need to get my 2D drawings ready in order to have the steel and aluminum plates laser cut.
More photos to come in the coming weeks!

[AlexFComp]

Hi everybody,

It's been a while since I haven't updated this thread.
Hope that you are all doing well.

So, I was able to finally complete my router build this week. It took a lot of time, sweat and fun!
It is now moving in X, Y, Z and I am able to control the spindle's speed and rotation. I ended up going with a recommendation that I got here on the forum for the CNC Controller: Acorn CNC. It was pretty easy to setup, even if you have a rather basic knowledge with electric parts (I am a mechanical engineering guy after all).

I attached a couple pictures of my build to this post.

The frame itself is built with aluminum extrusions as you could already see in the previous posts.

I went with steel and aluminum sheet metal plates that I got laser cut by a local supplier. I had to tap and countersink a LOT of holes after that! That was the most annoying part I'd say. I ended up renting a magnetic drill to countersink most of the holes because it wasn't stable enough by hand.

Regarding the stepper motors and drivers, I went back to where I sourced my linear rails and ball screw: Fred at BST Automation.
I ordered closed loop stepper from him: two NEMA 34 with 8.5N.m of torque for the X axis (maybe a little overkill, I know, but at least I still get a good amount of torque at higher RPMs), one NEMA 23 with 3N.m of torque for the Y axis, and one NEMA 23 with 2.2N.m of torque for the Z axis.
I also got a full Huanyang 2.2kW water cooled spindle kit with a genuine VFD, and three 360W MeanWell power supplies to power all motors (could have been replaced by a single one but I wanted to keep it modular in case I need to change something later).

For the control box, it took me a couple days of patience to properly wire it but my first attempt was the good one!
The goal was to power everything, including the water pump, with one switch. Because the input current of the VFD is 15A and the total input current for the stepper motors is ~11A, I needed to find a switch that could handle these 26 Amps at 220V. Quite hard to find, so I decided to use a 36A starter contactor with a rocker switch. Although I doubt that the machine will ever draw 26A when running, I'd prefer to be better safe than sorry!

I also took the time to build a Fogbuster-like coolant system that would help cutting aluminum more efficiently when needed.

Overall, I am pretty happy with my build! It took me a long time because I was doing that during my free time, but I am eager to try it out with a first machining job. Maybe next week.

The last things that I need to do is add a dust collecter shoe to the spindle for wood and RenShape jobs, but also an extra clamp to the spindle assembly to make it just a little stiffer.
The gantry doesn't seem to move much at all, so I think that I should be fine with its overall stiffness.

Then, I also want to wire limit switches to easily zero the machine, plus a Z touch-plate that I would fix in one corner to make tool changes easier.

If you have any good products to recommend for dust collection and the Z touch-plate, I'd be interested to know. I have a shop vac with an internal filter bag that we usually use to collect carbon fiber dust because it can trap small 0.1 micron particles. I could use it the same way to collect dust. But I see a lot of systems where people add a cyclone dust collector between the machine and the shop vac. Is this something that you'd recommend ?

Anyway, that's pretty much it for now.
Cheers!

Alex