Another build thread... JoshNZ

[Ljohnsaw]

Mike,
Thanks for that second drawing (turnbuckle)!  I'm going to incorporate that to solve two problems.  One is the resonate vibrations (not too bad).  The second is when I rebuilt my head and made it wider, I messed up and made the back set of wheels too close together (about an inch?) which makes it difficult to push.

[mike_belben]

glad to be useful john. 

[JoshNZ]

I agree with your description of the problem. It's not severe enough that I'm going to go to the lengths described in your solution though.. I thought about that too, extending the top plane past the legs and bracing on the outside but it's just getting too crude and unweidly for me.

SHS and RHS square and rectangular hollow section, I guess the steel merchants here abbreviate to that.

I've added two lengths of SHS 2", 1/4" wall, to the sides of the rear posts. That's stiffened it quite a lot - I didn't think so at first but I took a before and after video of me rocking it as much as I could and giving it one heavy nudge as hard as I could, and the difference is quite obvious in the video. Was easy enough to add and easy to paint without removing anything, so I'll see how that goes first. I'll load it back on the bed tomorrow.

Appreciate you taking the time to go into details though!

[JoshNZ]

Well it is night and day with the added box section.



 

I didn't have enough length to go the whole way unfortunately but I went past the bracing which should count for something.

It is slightly stiffer but I think what's made the difference is changing its resonant frequency which was certainly noticeable in the before/after video. Doesn't seem to get into its unruly harmonic now.

I also added a tensioner to the jackshaft while it was in the workshop. Should've done that from the start. I could hear something slipping the other day, decided to write the board off and ram carriage into the log, and that second pair of belts is what gave out. Band came to a complete stop - interestingly, I didn't get any kind of wave in the board.



 

Ive got one more problem to solve I was wondering how you guys would go about fixing this dent in the track where the carriage head hit. a field fix without power or air not a workshop fix hah. It could have landed on a weld... But no, about exactly half way between welds and cross members too. The divot isn't so bad but the angle length is swollen at the bottom. I can feel it when pushing the carriage but can't seem to see any noticeable mark in the boards.

[Crusarius]

Your wheels ride on top and rub the sides. Just take a file to it and smooth it out. That divot will not effect performance at all. just annoying more than anything.

Oh I see the bulge in the angle now. forgot thats what you did. That is part of the reason I chose not to do angle in that direction.

I still would think file the top and beat the rest back into shape with a hammer. Should still be fine.

[mike_belben]

agreed.  


glad youve got the shakes tamed down without a major overhaul. 

[trimguy]

Take a piece of scrap steel and lay flat against the edge and crank it in with a C- clamp.

[Ljohnsaw]

The top of the rail doesn't look harmed.  If not dinged, just file it off.  If there is a little dent in the top, hold a 10-12 pound sledge on the left side and wack the right side with a 2 pound hammer (I like to use the flat side of a ball-peen hammer).  A few good hits and you will just need a little file cleanup.

[fluidpowerpro]

Regarding your belt tensioner. Wouldnt you want to push both pillow blocks in the same direction? The way you have it, arent you going to cock the pulleys crooked to the belt?

[fluidpowerpro]

Ive got one more problem to solve I was wondering how you guys would go about fixing this dent in the track where the carriage head hit. a field fix without power or air not a workshop fix hah. It could have landed on a weld... But no, about exactly half way between welds and cross members too. The divot isn't so bad but the angle length is swollen at the bottom. I can feel it when pushing the carriage but can't seem to see any noticeable mark in the boards.


I would lay a piece of thick flat stock next to the edge of the angle where it is bulged. This will give you a flat surface to push on with a BA (Big Ass) C-clamp.

[JoshNZ]

Yeah I was thinking I'll need to put something beside it to hit, not much there to get purchase on. Not sure I have any BA rated clamps so will have to be a hammer job.

When I tighten the front pulley block (move it left in photo) the tensioning belt drags the back pulley block around it. I actually did start with them on both sides and soon realised it was a mistake, soon as there was tension the back block slide to the end of its slots. Now the process to add tension is back the back one off a half turn, crank the front one up a half turn, check, etc. Assuming it was in alignment. There is only ~1/16th between the pulley and beam so needs to be perfect.

[JoshNZ]

The eccentric cams for shifting pillow blocks for band alignment are exactly the same. Only needed two of them, one on each block on opposite sides. The band will take care of force on other two sides for each block.

[fluidpowerpro]

I see now. So the front one pushes to tighten, and the back one acts as a stop....

[JoshNZ]

That's it 

[RAYAR]

Hi JoshNZ, next time you have your mill at home or the shop, add corner braces to the rectangular frame of the top of your carriage. If you can't do the front ones due to clearance issues, at least add them to the back part. That would help with torsional movement of the carriage and stiffen it further. Good to hear that what you've done so far has helped a lot.