I had a problem with the bungee cords losing tension at the extra end of the sled travel. this was causing some issues with chain slack and jerking of the chain.
The new layout replaces the bungee with free hung weights which keep constant tension on the chains at all corners of the work surface.
I made two weights for each side, a 5 pound weight that stays attached all of the time and a 25 pound weight that can be removed when not in use or if I have to adjust the chain.I made then out of quick cement from Home Depot and some plastic buckets for molds
The weights were hung with wire cable. One pulley is used at each end of the top support to transfer the downward force to the idler gear that were attached to bungee cords before.
The cables run to the opposite end of the top support from the chain it is connected to. That is the tensioner for the right motor chain hangs from the left end of the top bar and the left tensioner weight hangs from the right end of the top bar.The pulleys that were used for the bungee cords were mounted on the same post and used to keep the cables from getting tangled and out of the way.
Yes, still using the sprocket also using the metal ‘S’ that was used for attaching the old bungee cord to the sprocket. The only difference is the way the tensioning force is a weight instead of the bungee
I had a design of running the cables down at the center but it was a mess. It needed two pulleys per line.
About the weight. I was guessing. For a while I had a 8x8x16 cement block that weight around 30 pounds and it worked great so I went with the same. I’ll give using less weight a try. The reason I do not use the blocks any more is because I dropped and broke one of them. Besides the rounds weights look cooler
if you go to a auto repair shop you can get the old metal disk drums for dirt cheap maybe free and they are nice and heavy. you can get pullys from china for $1 each
what is that silver hardware in the center where the two chains cross each other? Looks like a wood screw with a big washer and perhaps the two idler gears behind it??
ideally you want to have the weights < 2x the minimum chain tension from the
sled so that the net tension on the motors is towards the sled (so you don’t
have to worry about backlash on the gears)
on the stock frame, the min tension is just over 3 pounds, so 5 pound weights
are about right (assuming that everything works)
I think he stated that those are the rollers that came with the Maslow which are normally used for the bungees. Looks like they are stacked on one screw and the cables ride on the rollers.
I borrowed from @GaryInTulsa and cobbled together what you see here. 5 lb. weights, and paracord. I stacked the bearings that came with the machine on a nail with small lock washers (the size of the inner ring), and fender washers to shim it out from the board, between the bearings and on the end of the stack.
I cut out some letters for my daughter tonight and it worked flawlessly. Right now I can’t reach the upper corners without the slack chain/sprocket interfering with the bearings in the middle of the top bar. I will add extensions near the end of the motors to get the chain up out of the way and shorten the reach of the slack chain. I may add 2-3 lbs. on each side but it is working well with 5 per side. Almost forgot I put eye hooks half way between the pully and the bearings. Hope some find this useful. Thanks Gary.
The reason I finally got around to posting pic is because I had to breakdown the machine to move it to a new location. At the moment not sure when things will settle down enough to be able to set up the Maslow again
I used the bearing that the bungee would normally go on as wire cable guides to keep the cables from touching. It’s not the best picture but they can be seen right in the middle of the top board. the two bungee pulleys and a large washer all on the same nail
