06 Nov Carriage and Beam Work
The next biggest things that need to be added are the drive wheel and motor to the beam. Those items will make the beam much more difficult to manage should it need to be removed which it does in order to paint the carriage and to prep the beam for the raise/lower mechanism and the blade guides. So instead of moving forward with the bigger items and kicking myself later, I decided to knock out some of the less glamorous items.
When we built the carriage, we didn’t finish up some of the smaller details around the rollers. I cut and fit a piece of steel to go behind the hub to finish closing in the roller.
I had also planned to add a brace to the top of the hubs to help transfer the load from the outside of the hub back into the uprights. I cut and fit another triangular piece of steel for this location.
Thinking ahead to the raise and lower mechanism, the acme rod and extension shaft will be mounted off the side of the carriage. The base of the assembly will ride in a thrust bearing and that bearing needs somewhere off the side to mount. I had a couple pieces of square tube from making the carriage that I welded to the side of the carriage to create a platform that the bearing holder will mount to.
I marked the locations of the uprights onto the beam for future reference and I can now remove the beam from the carriage. I made a pair of wooden rails that the linear carriages can slide onto in order to keep the balls inside the carriages. I set these on blocks so they were pressed up against the linear rail that way as the beam is lowered, the carriages would travel onto my wooden blocks.
The carriages can now be removed from their mounting plates and the linear rails can be removed from the uprights. When I attached the mounting plates, I very lightly welded them on in a few places so I didn’t heat up the bearing and melt the seals. With those carriages off, I could come back and fully weld the mounting plates onto the beam.
Before I move onto painting the carriage, I still need to cap the tops of the uprights. I used some scrap 1/8″ steel cut into squares to cap the tubes. I still have to add the bracing along the side but I’m waiting until the saw is full assembled so I can make sure it is stable enough that I don’t have to add another pair of acme rods at the rear to stabilize it.
Paint time! I followed the same procedure that I detailed in my Painting the Track post. I ran out of top coat and metal prep so I wasn’t able to paint the beam at this time but I did apply paint to the mounting plates on the beam so I’ll be able to easily paint it once it’s back in place.
Between coats of paint, I started working on a few parts starting with these nut holders which will mount to the underside of the beam. The acme rod will pass through the beam and thread into the nut. The box around the nut will prevent it from spinning which will raise or lower the beam. I decided to do this instead of welding the nut directly to the beam for more versatility. If I need to change of replace the nut in the future I can easily do that.
I made a flange mount for the nut holders again for versatility. With the bolt on flange, I can shim the whole assembly if I need to align the acme rod.
The side pieces for the holders were cut from some excess 1/2″ steel, laid out around the nut, and tacked in place. The nut was then removed to complete the welding along the outside seams.
The beam needs holes drilled through it in order for the acme rod to pass though it. The rod is 1-1/2″ diameter and I drilled a 1-3/4″ clearance hole in the top and bottom of the beam.
Since I have more of the linear carriages and the two offcuts of linear rail, I decided to use those for the blade guide supports. The guides will be mounted to a horizontal beam extending from the carriage. The guides will also connect back up to the linear carriage. This will add some extra support to keep the guides from sagging as they are fully extended. (So the guide supports will be L shaped). I spent some time arranging everything on the underside of the beam so I could be sure this set up will work. It looks like I’ll be able to pull the blade guides all the way outside of the carriage opening so the theoretical max cut width of the mill will be 77″.
I’ll start by mounting the nut holders over the clearance holes. I start by marking, drilling, and tapping one hole.
I’ll install the first bolt and mark, drill, and tap the second hole. With two bolts installed, I’ll mark the 3rd and 4th holes.
The linear rails are set up so they are as far towards the back of the beam as possible. The mounting plate is the determining factor here as the carriage will need to clear it. The left and right position is set by the nut holders. The offcuts I had were almost long enough to span the distance from one nut holder to the other. The idle side has the rail right up against the holder and the drive side has the rail within an inch or two of the holder.
With everything lined up, I’ll start mounting the first rail. I’ll mark, drill, and tap the first mounting hole then installed the rail and repeat the process for the last mounting hole.
The second rail can then be butted up against the first and I use the carriage to bridge the two rails which aligns them. I’ll make sure the far end is parallel to the beam and mark, drill, and tap the first and last mounting holes.
I’ll reinstall the second rail and align it again to the first. Once I’m happy with the alignment, I’ll mark, drill, and tap all of the mounting holes.
Next time we’ll move onto the drive wheel and motor.
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