Re: table base
Posted: Tue Nov 16, 2010 10:22 pm
Nice conversion Bob! I like the idea of the table leveling screws.
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table base
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Re: table base
Posted: Tue Nov 16, 2010 10:50 pm
Very interesting! Table design really looks nice. I can see a hint of your adjustments you mentioned. I see the detail of your X axis support - sort of a track right? I belive the Shark Pro Plus has a slightly large bearing rod, but hard to say accurately. Thanks for the info.. Gives me some ideas.
Re: table base
Posted: Thu Nov 18, 2010 4:44 pm
The bearing rods are the same size as the original shark pro, 20mm dia. I cut the new supported ones to the same length as original.
The rods are supported their entire length by the support extrusion that is bolted to the rod. As the new rods are the same dia as original, I used the original hole locations in the gantry side plates and just cut back the support extrusion about 3/8" on each end to leave the side plates unmodified.
When assembled, support extrusion fell almost exactly 1/2 inch from the flat gantry back plate (that has the name cut in it). I made up the gap with 1/2 x 2" solid aluminum bar, which was overkill, but the strength improvement was quite substantial. The 3 pieces (bearing extrusion, 1/2" bar, and the gantry back plate) now bolt together along the entire length of both linear bearing rods to make an very stiff assembly. I'll attach a picture that shows it better. The lower 1/2" x 2" bar is tinted red in the picture to help you see where it sandwiches in.
The z axis assembly now has a 1/2" aluminum plate sitting just behind the z axis rods and bearings. That plate is used to mount the bearing races for the x axis and also stiffens up the z axis "box" quite a bit. All 4 sides of the z axis box bolt to the internal plate. You can see the 3 bolts on the right side plate in the picture. The side plates were replaced with aluminum as well to keep from cutting up the original plastic ones.
Hope this clarifies how it all goes together. I'll attach a picture of what the linear bearing rods and bearings look like too.
Bob
The rods are supported their entire length by the support extrusion that is bolted to the rod. As the new rods are the same dia as original, I used the original hole locations in the gantry side plates and just cut back the support extrusion about 3/8" on each end to leave the side plates unmodified.
When assembled, support extrusion fell almost exactly 1/2 inch from the flat gantry back plate (that has the name cut in it). I made up the gap with 1/2 x 2" solid aluminum bar, which was overkill, but the strength improvement was quite substantial. The 3 pieces (bearing extrusion, 1/2" bar, and the gantry back plate) now bolt together along the entire length of both linear bearing rods to make an very stiff assembly. I'll attach a picture that shows it better. The lower 1/2" x 2" bar is tinted red in the picture to help you see where it sandwiches in.
The z axis assembly now has a 1/2" aluminum plate sitting just behind the z axis rods and bearings. That plate is used to mount the bearing races for the x axis and also stiffens up the z axis "box" quite a bit. All 4 sides of the z axis box bolt to the internal plate. You can see the 3 bolts on the right side plate in the picture. The side plates were replaced with aluminum as well to keep from cutting up the original plastic ones.
Hope this clarifies how it all goes together. I'll attach a picture of what the linear bearing rods and bearings look like too.
Bob
- bearings
Re: table base
Posted: Thu Nov 18, 2010 6:38 pm
The one concern there is with this is a buildup of material on the top of the rods since the rod is suported and material cant fall off. I would suggest if you are doing something really messy have a slight air flow over the area. Nice conversion we use a similar supported shaft for are longer bases.