You beat me to it I was going say use a bigger hammer..:stickpoke
Lou
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Probably going to make one out of MDF with sheet metal glued on top...
I also toyed with the idea of placing a third roller there, 'exactly' under the drum.... Might yet... Gonna run it like this with the solid plate first though and see how she performs...
I was planning on grinding it down a little, but I couldn't do that in the house, and it would also mean talking it all 'completely' apart.. So I tried the hammer approach first, because I'm lazy.. Worked fine...
I guess it wasn't out much.. other than a few scratches from the hammer head, I couldn't tell the difference looking at it.. but it definitely fixed the sticking problem...
Normally, there is a hard surface backing up the sandpaper so the sanded material's surface is evenly sanded. The sheet metal surfaced MDF should work as long as the belt can't snag the edge of the metal. Bend it around the corners of the MDF ends and screw or glue it to the ends.
If your rollers are not slightly crowned to help the belt stay centered, an easy solution may be to add one or two layers of 2" wide masking tape to the center of the roller at the rear end of the belt. That would simulate a crown.
CarveOne
Was wondering how I could do that cleanly, so I'm also kicking around the idea of just using a round over bit on the MDF, and then routing a recess for the sheet metal to sit flush in...
Hopefully, I won't have to mess with any of that... It 'seems' to be tracking good now... but I won't know for sure until I get it under power and let it run for a while, adjusting it, etc..
It doesn't need much of a radius. Just no square edge that can wear the belt and/or cut it.
The tracking can change under sanding loads, probably more so with narrower belts though. If it does so with this wide belt, the tape method can help keep the belt from wandering.
CarveOne
So I cut up and installed the infeed and outfeed tables and rough adjusted them.. I also made the center support table, but I need to drill the mounting holes in the 1/4" steel plate at the bottom.. This thing is getting a little heavy/unwieldy to handle by myself, so I need to get e neighbor over to help me move the thing onto some sawhorses before I drill the holes and mount the table... none of them have sheet metal on them yet, but I don't need that to get this going.. I can do that at the end, just before I start running the thing..
I also, picked up some more steel and gas for the welder.. I think I have enough to make the main frame, so I can get going on that in the next few days too...
Slowly but surely, I'm moving along... I'll post some more pictures soon...
A little more progress...
Drilled the mounting holes for the center table in the 3/8" steel plates at the bottom of the feedbelt frame and mounted the table.. Rough adjusted it and now I'm ready to start building the main sander frame..
Gonna glue some sheet metal (probably 18g) to the tops of the feedbelt tables when I do final reassembly and adjustment when the whole thing is fabricated.. Also need to radius the edges of all three pieces of MDF
http://www.mountaincraftworks.com/pi...eedbelt017.jpg
http://www.mountaincraftworks.com/pi...eedbelt018.jpg
http://www.mountaincraftworks.com/pi...eedbelt019.jpg
Looking into lift systems..
Was looking at these, thinking I could just drill holes and weld them to the 3/8" plate at the bottom of the feedbelt frame (four places), and then have some 1/2" Acme screw machined (shoulders) for my purposes locally..
I thought the price was right, but then the guy is asking $15 for shipping.. woahj! It's a freakin' 1/2" 'nut!'
Anyone know where to get these at a 'reasonable' price?
http://i.ebayimg.com/t/1-2-10-ACME-L...%7E%7E60_1.JPG
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<table class="vi-is1" border="0" cellpadding="0" cellspacing="0"><tbody><tr><td colspan="4">1/2"-10 ACME LEAD SCREW HEX NUT 1-2984-50N
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Subject to credit approval.See terms</td></tr></tbody></table>
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Use Expedited Shipping to get it by Feb. 18
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McMaster-Carr #94815A107 $2.52 each.
Shipping is usually around $5 for small items to me, but it may be more for you. The bad thing is you won't know how much shipping is until after you get them.
$15 for shipping is way out of line I agree Mark the guy is crazy..
Lou
Enco - Guaranteed Lowest Prices on Machinery, Tools and Shop Supplies
Enco usually has a 20% order discount (usually towards $100) or free shipping (smaller orders) depending on the month. Poke google for a bit.
Enco is offering free shipping on any size order this week.
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Hurry! Offer ends Friday, 2/17/12.
The ACME Screw I bought from McMaster was black.. looks anodized.. The nut I use on it is a delrin nut...
What type metal is that called? I'm thinking that would be the 'alloy' listed on the ENCO website.. Is that correct?
ENCO has several options, both nuts and screws.. I'm not sure what is what..
The cheapest option is the keystone nuts and the low carbon steel screw..
How much difference is there in smoothness or binding or whatever between the more expensive materials I used on my CNC machine and the materials I am considering from ENCO (steel hex nuts and low carbon steel)?
The belt feed table is obviously pretty heavy, and will be even more so with material on it being fed into the sander...
The idea is to have four vertical ACME screws, one in each corner, connected together via gears and chain.. and the four screws working together to lift and lower the table... Looking at about 6 inches of travel...
You guys think the 1/2"-10 low allow steel screws will work okay? I'm reluctant to go bigger or more starts, as I want to keep resolution as high as possible... But if that is necessary, I 'could' do it via gear reduction at the adjustment knob drive shaft (already planning on at least a 2:1 reduction as it is)..
also, I need to use some sort of bearing blocks, top and bottom.. Looking for something effective but affordable... Would be nice if I didn't have to use thrust washers and screw collars.. Is there a solution that does what I need without breaking the bank?
You might want to have a look at this assembly, for precision table height adjustments: Building a jointer - part 1
I too, considered making a table height mechanism using exactly the method you described. However, unless you are using a stretch-proof chain, and set screws to lock the individual sprockets onto the lead screw of each corner, synchronization is almost impossible. The link I listed above, seems to be a simple solution. Which still places the height adjustment mechanism under a single screw control.
I'm actually considering 3 possible methods, and one of them involved making two shafts with two cams on each with a screw to adjust the rotation of the shafts to lift the table up or down.. Rollers would be mounted to the underside of the table for the cams to push against...
The idea for leveling on that system would be to mount each end of the four shafts through threaded heim rod ends which could be adjusted up/down using nuts on their threads through a mounting plate..
The other method is to use four ACME screws and a bicycle chain underneath.. A smaller dive sprocket would be used for gear reduction, and on the opposite side a spring tensioned idler gear... and yes, set screw mounting of the gears on the screws for leveling of the system..
The reason I'm starting to lean this way is because with the cam method I'd have to install four 1/2" guide bars to lock x/y lateral movement of the table anyways.. and that means drilling the holes and installing shafts right where the screws would go anyways..
The other method I was considering was using a scissor lift type of mechanism, but I'm having a hard time figuring out how I would do 'leveling' of the table with that system...
you could always slave 4 steppers and CNC the height control :D