PiperPilots Fixed Gantry 8020 CNCRouterParts DWP611

[piperpilot]

Hey folks,

Starting a new build thread to discuss my next router. Really still building the first which is my 10x9 Oak Solsylva found here:

http://www.cnczone.com/forums/diy-cn...rst_build.html

But I see starting this one pretty soon as I want something bigger, better. Yes I have the bug.

Anyways...this design will be a fixed gantry design because I want it to be as rigid as possible. I am basing off of several designs.

First off Ilya's 8020 design. I am kinda using that as my base. I am adding the CNCRouterParts "High Z" for added rigidity. I will also be adjusting the size a bit. I am undergoing a build of a movable table and enclosure which I sized at 35"x35" I want to use up as much of that space as possible. I'm hoping to get around 22"x22" or so when I'm done.

Anyways...I'm doing the layout in sketchup and have run into the first little challenge. Seems that when using 6" CRS with the High Z, the leadnut holes don't line up between the screw holes in the CRS. I suspect when I add bolts/nuts to the CRS, I will hit them with the leadnut. A couple screenshots are below. I also included a screenshot of where I am mounting the leadnut...am I missing an alternate location? There doesn't seem to be one that is dead center for 6" CRS.

BTW...I am using 3030 as the horizontal member for the gantry that the CRS bolts to. I considered using 3060, but I think if I do that, I would have to change to 7" CRS or use 2x2.5" with the mounting brackets that CNCRP sells.

I do have the option to drill the CRS off center...is there a problem with that?

Curtis

[CarveOne]

I am a big fan of using red oak instead of MDF on the smaller machines. I spent around $90 on red oak for my first effort, the Solsylva 25x37 and it was well worth it. If you need a 2x4 just laminate two 1x4 pieces. It is much stiffer than MDF, poplar, or pine lumber and looks much better than the others with clear finish. Bolts don't crush the oak when tightened securely. I consider it to be a lower cost material versus aluminum that is almost as good for building these machines. For no more oak than you used on your 10x9 the cost is not much of an issue at all for what you ended up with. Looks good.

If you want 35" x 35" cutting area, draw a square of that size as a "keep-out area" and then draw everything else around it and include any additional distance you need for limit switch operation. The center of the cutter should be able to cut around the 35" x 35" square on all sides. You will find that the amount that the cutter is forward of anything on the gantry that causes interference in the rearward travel, and the width of the Z assembly will interfere with the sideways travel, needs to be allowed for.

One thing I found with the DW611 is that the big yellow head on the router will need to be allowed for so that it can be raised to full Z height without hitting a motor mount plate at the top of the Z assembly. My router mounting plates could be 1/2" shorter than they are now if I had purchased the DW611 sooner than I did. The Z assembly had already been built by then.

It depends on how far off center the holes would be. Can you stagger the holes, alternating between two 8020 slots or just make two rows of equally spaced holes? CNCRP carriages need at least 1/2" of the rail edges overhanging the 8020 beam on each side.

CarveOne

[piperpilot]

Thanks CarveOne,

First off...good thing about using the "High Z" is that the motor and mount travel up and down with the spindle so there is nothing for the DWP611 to hit at the top side. As soon as it arrives, I'll throw up a quick model and add it to my design to check it all out. Thanks for the tip to look out for that!

I figure if I shift the CRS mounting screws 1/2" off center, I should be able clear the screw heads. Attached are two shots...first looking down the end of the leadscrew. You can see the clearance there...if I were to move say another 1/8" I would be dead center between the rows of screws.

Second screenshot is looking straight at the back so you can see how far off center it is.

Now here's another thought. Unfortunately 8020 doesn't make a 3045, that would be great...but I can take the 3030 and lay a 3015 on top of it effectively making a 3045. It would require some access holes for the screws to hold them together. This would allow me to move the CRS mounting holes even further apart to clear the leadscrew. Other option is to use 2x1545 screwed together...that would give me my 3045 as well.

Other option is to switch to the 2 1/2" CRS and mount it that way. If I did that, I could switch to 3060 for the cross member.

Not sure if I am overthinking/over engineering this or not. I'm not sure about the physics of not having everything lined up completely in the middle. The way I see it, there is no way to move the leadscrew to the middle without going the 3060/7" CRS route...but I'm not sure how important it really is. Obviously Ahren designed the High Z to be used with 6" CRS...but he might have meant it to be with the R&P setup...not the leadscrew.

Anyways...now I'm rambling...any further comments on the above would be great.

[vtx1029]

Is there clearance for button head cap screws if you go with the 6 crs? T nuts are not super expensive if your only buying a few.

[piperpilot]

Is there clearance for button head cap screws if you go with the 6 crs? T nuts are not super expensive if your only buying a few.

I see, you are saying instead of using nuts on that side and 3/4" carriage bolts, go with T nuts inside and use the button cap screws instead. Hmmm...I'll have to test it out and see...those are much lower profile than nuts, so it might work out. That would allow me to center the screws on the CRS.

Lemme tweak the model and report back.

[vtx1029]

I had another idea for you, super cheap too!

tap the holes in the crs and drill a hole thru the extrusion and run bolts from the back side of the extrusion

[piperpilot]

Even with button heads, it doesn't look like it will clear. Screenshot attached below...this is of the holes still 1/2" off center in the CRS. The button head would still be too close to the leadscrew for comfort.

I'll have to think about and model the tapped holes. That might work out good.

[CarveOne]

I completely misunderstood your problem with the rail until I saw the picture of the lead nut. How about countersinking the rail enough to use flush mounted flat head socket screws? Countersink bits are cheap (even at Lowe's) and I guarantee that you will find other uses for it later.

CarveOne

[ahren]

Piperpilot,

The issue is that the High Z was not designed to run on 6" steel on 3030 -- it was designed for 4" steel on a piece of 3030. The 6" steel hole spacing was for those using 1545 extrusion for a gantry, which is a viable possibility as well. For the ultimate in stiffness though, 3060 and the 2.5" rails is the way to go.

I also need to update the high z model on our site -- there's a new version out that provides an extra set of mounting holes to allow for higher mounting of the z carriages. I need to dig up my old copy of Alibre to get it converted to sketchup, however. I can send you a 2D drawing later today. We still have some of the older style, so no need to scrap your design, but you might want to look at the new one as an option.

Ahren
CNCRouterParts

[piperpilot]

Ahren,

Modeling up what it would look like with 3060 right now. If you have that 2d of the new High Z and/or the sketchup model of it...that would be great. I'd like to compare the differences.

Also, you don't seem to have the model for the "Gantry Rail Clamp" on your site either. Not horribly important for the model, but I would love to have it to double check all clearances, etc.

There seems to be lots of references for the moving gantry models out there, but not a whole lot of folks that have done fixed gantry.

Thanks again!

Curtis

[piperpilot]

OK...did some more thinking and design work. I had originally looked at the R&P system to solve my problem of the steppers sticking out the side and taking up an extra 3 inches of space. I also didn't like the design because the carriage had to stop at the edge of the vertical uprights which meant that the spindel could only go to about 2 inches from the edge.

So below are screenshots of my new thought. Using the 3060 for the horizontal member. Using the 2 1/2 CRS. Using 2x 1530 for the vertical uprights. You can see that I have those mounted to the back of the 3060 as well as have the 3060 sitting on top of one of them. I will use alum or steel bar stock to provide additional bracing.

The reason for having the 3060 set foward is to allow the carriage to pass in front of the vertical supports. This will give me 3-4 inches of extra travel and allow the cutting head to extend to within 1/2 or so of the edge of the table.

Now the stepper...I have it mounted on top of the 3060 and am looking at driving it with a belt. This keeps the stepper from hanging that 3" off the left side and allows me to make the router that extra 3 inches wider.

So a couple questions about pulley/belt systems. First off...I don't see how I can tighten the belts in this setup. I guess maybe a 3rd roller on some kind of slide adjust? Next, any suggestions on pulleys/belts? Ideally I'd like the pully to be a 1:1 and just provide a direct drive to move the stepper out of the way.

Thanks again for everyone's support!

Curtis

[vtx1029]

First off...I don't see how I can tighten the belts in this setup. I guess maybe a 3rd roller on some kind of slide adjust? Next, any suggestions on pulleys/belts? Ideally I'd like the pully to be a 1:1 and just provide a direct drive to move the stepper out of the way.

Thanks again for everyone's support!

Curtis

You could put a pivot bolt in the mounting bracket for one bolt and a slot for the second bolt. Or A pivot and a spring to keep constant pressure on it if the belt had some stretch.