[pippin88]

The trucks should be accurate. Mine are 30mm center to center in the direction parallel to the rail, and 32mm across.

The rail holes are usually a bit inaccurate as they appear to be drilled by hand.

You will probably want to use something other than MDF for that flat plate. It gradually compresses and your screws will before loose over time.

[fretman_2]

I will look at using something else...or maybe gluing in some hardwood dowels to screw things onto.

Tnx,

The trucks should be accurate. Mine are 30mm center to center in the direction parallel to the rail, and 32mm across.

The rail holes are usually a bit inaccurate as they appear to be drilled by hand.

You will probably want to use something other than MDF for that flat plate. It gradually compresses and your screws will before loose over time.

[Louis_Cannell]

you could use m4 threaded bar or nuts clean trough with repair washers on reverse, injecting epoxy ARALDITE or similar into predrilled screw before set would fix screws but be permanent, looking good beginning to come together and resemble a machine.

[fretman_2]

Yes...something like that Louis. I've also thought about cutting two grooves and adding some hardwood strips on the back side running parallel with the Z axis. Those would stiffen the plate and add something to attach to.

you could use m4 threaded bar or nuts clean trough with repair washers on reverse, injecting epoxy ARALDITE or similar into predrilled screw before set would fix screws but be permanent, looking good beginning to come together and resemble a machine.

[Louis_Cannell]

if you use epoxy may be possible to wax screw and remove just before set would give you a solid fixing it would not move or compress anyway

[fretman_2]

Louis...I'm trying to visualize what you're saying. The M4 threaded bar...not sure how that would work??

you could use m4 threaded bar or nuts clean trough with repair washers on reverse, injecting epoxy ARALDITE or similar into predrilled screw before set would fix screws but be permanent, looking good beginning to come together and resemble a machine.

if you use epoxy may be possible to wax screw and remove just before set would give you a solid fixing it would not move or compress anyway

[Louis_Cannell]

Nut on top or front of rail loc-tite to secure drilled straight through beam large penny washer at rear with a Nyloc or again standard nut and Loc-tite looking at my 20mm supported rail more than enough room to clear bearings over M4 nut abobe rail mouning plate.

With the eopxy drill then inject, while soft before set completely, wax a screw drive in and remove, in effect tapping the epoxy and epoxy reienforced MDF which would be stable as large amount orf epoxy should be absorbed or pushed into MDF under pressure. Loc-tite again could secure screws in case of vibration.

[fretman_2]

Hummm....right now those rails are secured to the beam by drywall screws. They're very tight and there's no movement of the rail at all. I probably shouldn't have used wood screws, but after I paint the gantry, I may put a drop of super glue on the wood screw then screw that in. That should hold it tight. Amazingly...I didn't have any splitting due to the screws. I drilled pilot holes and countersunk.

I've already got a different design for the gantry in mind as a later update...LOL.

I'm going to do a little test...drill a pilot hole in a scrap piece of 3/4" MDF, then screw in the dry wall screw, then remove it. I'll wick some water think super glue into the hole, let it dry, then screw in the dry wall screw. I'll see just how much force it takes to remove it.

I found a thread that speaks to using CA for protecting a threaded hole in MDF...

http://www.cnczone.com/forums/jgro-r...126-posts.html

Nut on top or front of rail loc-tite to secure drilled straight through beam large penny washer at rear with a Nyloc or again standard nut and Loc-tite looking at my 20mm supported rail more than enough room to clear bearings over M4 nut abobe rail mouning plate.

With the eopxy drill then inject, while soft before set completely, wax a screw drive in and remove, in effect tapping the epoxy and epoxy reienforced MDF which would be stable as large amount orf epoxy should be absorbed or pushed into MDF under pressure. Loc-tite again could secure screws in case of vibration.

[manofmanyhats]

I've already got a different design for the gantry in mind as a later update...LOL.

Welcome to the slippery slope of DIY machines

[Louis_Cannell]

Anything that soaks into the MDF and solidifies it to stop compression and breaking down of fibres which would allow screws to loosen will help even Super glue, Varnish etc will reenforce the screw hole and surrounding area it will look better than screww an inch to long and bending the end over

[fretman_2]

Cool...I use a good bit of polyurethane in my guitar builds...a subject you know well. I may soak the top of holes with oil based poly before painting the gantry.

Anything that soaks into the MDF and solidifies it to stop compression and breaking down of fibres which would allow screws to loosen will help even Super glue, Varnish etc will reenforce the screw hole and surrounding area it will look better than screww an inch to long and bending the end over

[fretman_2]

I'm going to try and cut out the gantry sides this weekend. I want to make sure that I get these exactly positioned correctly...exactly opposite from each other and on center with each other. Other than making sure I get the holes drilled in the right spot on the gantry beam, what can I do to ensure the sides are in position correctly with respect to the beam and themselves?

Tnx,

Attachment 319238

[Louis_Cannell]

On my build I just let the beam in to my 25mm gantry plate 4mm either side for alignment and rigidity if you have a spare 1mm even a 0.5mm pocket each side would allow good alignment even if you have to let bearings in 0.5mm too to accomodate shift.
apart from that two dowels placed into beam and drilled into sides accurately or use thicker side and pocket everything in as I did.

[fretman_2]

Thanks Louis...I had thought about a pocket too. One of the things I'm considering is making a cradle that would attach to the gantry side, then the beam would be inserted into the cradle, then the gantry sides screwed to the beam. Then the cradle would be removed and the process done on the other side.

Here's a pic of the gantry side and cradle that would be CNC'd on my current machine...the cradle is on the left. I should make sure the cradle is just a thousands or two larger than the beam.

On my build I just let the beam in to my 25mm gantry plate 4mm either side for alignment and rigidity if you have a spare 1mm even a 0.5mm pocket each side would allow good alignment even if you have to let bearings in 0.5mm too to accomodate shift.
apart from that two dowels placed into beam and drilled into sides accurately or use thicker side and pocket everything in as I did.

[Louis_Cannell]

Seems like a plan for me it would add strength accuracy of assembly and rigidity!

[fretman_2]

Got a little more done yesterday. Cut out the sides or wings of the gantry on my Shapeoko2. I've shown two of these each on each side of the gantry but I think that I'm only going to go with one each initially. I can always add another on each side if I have to do so. I also cut out a jig-template that will aid me in drilling the screw holes in the sides of the gantry beam.

Attachment 320176

Attachment 320178

[fretman_2]

Ladies and Gentlemen we have a gantry. Will double check alignment, but so far so good! There's so much that I've learned that will carry over to my next build which will be a much smaller machine for cutting pickguards, control plates, and circuit boards.

[fretman_2]

The alchemist turned my MDF into aluminum...LOL. Painted with Rustoleum Hammered spray paint...

[Louis_Cannell]

Looking good will have to try painting mine brown so it looks like MDF

[fretman_2]

LOL!!!

Looking good will have to try painting mine brown so it looks like MDF