[LeeWay]

I am not able to see the images.

[Hartzell]

LeeWay: I re-uploaded the images, can you see it now?

Im going to order the stepper motors and drivers now. What do you think about this combo?
Motors:
【German SHIP】4 Pcs NEMA 23 Stepper Motor 270 oz in 1 9nm 3A 23HS8430 Bipolar | eBay
Drivers:
THB6064 MassMind Stepper Motor Driver Kit

[LeeWay]

I see them now. Thanks. Looks great.
The motors are probably okay, but the drives are questionable.

[handlewanker]

Hi.....it looks OK.....the broad mounting face on top should be plenty rigid enough.

I think that design for the bolt on crossbeam will work well as you can align it in all planes.......good work on the tapping.
Ian.

[wizard]

Hi…

Now on to to the bridge uprights. Have a new idea with the bridge bolted on top, see drawing. With this variant I will be able to chim if I need more height. Also gives more room for adjustments and future redesignin of the bridge. What do you think?

About those uprights, Ideally you will want to be able to move the Y Axis saddle such that the cutter clears the table by a good amount on each side. So many the front sides should be trimmed back a bit. How much depends upon how big of a cutter you plan on using and how much clearance you fell comfortable with. The problem here is the Y saddle needs extra space on the left and right travel extremes, that can make for a longer Y axis than you planned for. If you have a long Z axis capability you may be able to clear tools by retracting to the extreme on the Z, but I think it is more advisable to have proper clearance in the first place.

I hope this makes sense (it has been a very long night at work). At this point we don't even know if there is an issue as there is no gantry beam in your pics, no Y axis saddle and no Z axis. Once those are all stacked then we should know what the clearances look like.

[LeeWay]

She's a small one, but heavy duty.

[Hartzell]

Crazy idea?

[Pplug]

Crazy idea?

I like that design!

[wizard]

Crazy idea?

Yes crazy, as in not good. C channel is pretty flexible, if you have ever see construction workers carry 20 foot sections around you will know what I mean here. Beyond that you have the rails mounted on the legs of the C channel with no support. Finally mounting the rails front and back like that will be a difficult machining experience.

In a nut shell you have rather impressive machine structure so far. As such I would focus on a gantry design that is equal to the effort put into the rest of the machine.

[awerby]

What if that C channel was replaced with a box beam that has a slot taken out of it for the attachment to the ballscrew nut? It also seems that the table is a bit small, compared to the rest of the machine. It would be sturdier if the supports for the bridge were wider at the base of the machine, rather than narrower, as in the drawing.

[Pplug]

Depending on the thickness of the c-channel walls, and the length of the gantry, I don't think it would be a problem. As for machining, you would need to make some jigs to help position the drill holes for the linear rails.

My only problem is the forward supports linking the gantry to the y axis bearings. The way it's shown, you can't slide the x axis over as far as it could. That will limit the width of your table.

[handlewanker]

Hi, with this design you could have a fairly heavy flat plate across the X axis and bolt two thick wall pieces of angle iron to it......you don't need to go too high with the angle iron sides, just as wide as the linear rails is sufficient.

The idea of having higher sides to increase rigidity of the cross beam I think is not warranted......if you have a thicker base piece and heavy angles it will be rigid enough.....nothing will act against the material cross sections to make them flex or bow in the middle unless massive forces are envisaged......with a 10mm base plate....not even then.

Having two angle irons back and front for the linear rails, bolted to the plate, will allow you to adjust the width of the cross beam to get it dead parallel and square to the Y axis......which is impossible with a C channel unless you have it machined on three faces and hope it doesn't warp.
Ian.

[wizard]

Depending on the thickness of the c-channel walls, and the length of the gantry, I don't think it would be a problem. As for machining, you would need to make some jigs to help position the drill holes for the linear rails.

While I agrees that length and thickness are factors, if you need to buy the materials why not go with the simple solution.

As for machining, what has me concerned is getting the pads for the linear rail parallel to each other. If you have the machinery and time it doesn't make much difference. However if you need to pay somebody to do the job, then difficulty means far more dollars expended.

My only problem is the forward supports linking the gantry to the y axis bearings. The way it's shown, you can't slide the x axis over as far as it could. That will limit the width of your table.

Generally I really like the design of this machine. I just see this design as a weak point overall. The other bad point is that the C channel will become a collector of dust, chips and other nasties and a real pain to clean.

[daniellyall]

a simple way to do the X just have to 3in x 3in x 5mm box section for the uprights another couple of lengths in between then stick a length x 100 mm x 10mm plate between the uprights as a face for the Rails

[Pplug]

The best design for a gantry that I have ever seen is on my techno isel lc4896. The screw and rails are entirely enclosed in the gantry and rubber seals the length of the gantry seal out dust and debris.

[handlewanker]

Whatever design is used for the crossbeam, it has to bolt down onto the tops of the side columns.....that is the stage it's at.

To do that means you have to take into consideration that bolting relies on solid material to pull down on........the interface to the top of the column sides will be a flat plate each end........what gets welded to those plates is another story....you could use a C channel, but as Wiz said it will collect swarf and chips and clog the screw and rails.

Personally, I would have the rails in a top and bottom mode against the face of a plate as opposed to on either side of a channel.

You also have to allow for the ball nut housing to move between the rails, so this suggests two square steel tubes, one above the other, welded against a vertical plate with the gap between them wide enough to clear the nut housing.

The cross beam vertical steel plate could be a large angle iron (or a thick wall square steel tube) instead of just a flat plate.....thus killing two birds with one stone for bolting down to the column.
Ian.

[LeeWay]

The best design for a gantry that I have ever seen is on my techno isel lc4896. The screw and rails are entirely enclosed in the gantry and rubber seals the length of the gantry seal out dust and debris.

That makes it clean. It doesn't necessarily make it strong and rigid. We would have to examine the guts a bit to tell more about that. It does look to be well designed though, so may be solid.

[wizard]

That makes it clean. It doesn't necessarily make it strong and rigid. We would have to examine the guts a bit to tell more about that. It does look to be well designed though, so may be solid.

Often it comes down to intended purpose, rigidity is important but can be expensive if a use doesn't need it. The nice thing about the techno though is the design keeps the screw clean which can be huge from the maintenance standpoint.

[LeeWay]

I have really come to appreciate good design for way covers and protection on machinery. They can really lengthen the lifespan of parts by a long shot when done correctly. They also don't have to be uber expensive either.

[UA_Iron]

I have really come to appreciate good design for way covers and protection on machinery. They can really lengthen the lifespan of parts by a long shot when done correctly. They also don't have to be uber expensive either.

I was really impressed with Bosch stages. Fully sealed and either air pressure or vacuum could be applied for clean room purposes. A single point of lubrication would lubricate the both linear guides and the ballscrew all in one grease application.