[Mountaincraft]

So, I've had a couple setbacks.. When welding up the feedbelt frame, it distorted the unistrut slightly, bending it.. I was trying to avoid that by welding in small bits, but in hindsight I should have welded the business end of the strut 'first'.. So it's causing sticking on one side of the adjustable end of things.. So I gotta take it all apart, and grind that a bit, and then I think I'll reverse ends as the other end seems to still be straight and true...

When I picked up the used thickness planer I bought yesterday, I took a few minutes to check out how the beltfeed was installed and adjusted on it.. It's a smaller machine, with a larger diameter drum, open ended on the feed, with the adjuster raising and lowering the drum housing...

It's a smaller belt in both width and length, and it appears that the rollers are not crowned at all.. It also doesn't use any 'springs' but just has a screw tensioner on each side of the one roller...

I think the key will be to get the 'fixed' roller 'very square to the frame, and then just carefully adjusting things... In any event, I have a plan 'B' should I not be able to get the belt feed working...

The plan is to build the main frame, using vertical half inch rods at each of the four corners for the belt feed frame to slide up and down on.. These will keep it from shifting or canting as the mechanism underneath adjusts the height of the belt feed frame.. I'm planning to initially, use 1/2" threaded rod in these spots and just use wing nuts to adjust the height in the four corners during start up and initial testing.. I'll build the beltfeed lift/adjuster last..

I also ordered the aluminum Tee slot and knobs that are to be used on each side of the drum enclosure.. These will be for mounting and and adjusting a tilt fence on top, where the top of the drum will be exposed (removable cover) for hand feeding it the opposite direction (like many of you have your drum sanders set up)...

Have most everything worked out in my head.. with dust extraction being the last major hurdle...

[Mountaincraft]

Okay, a bit more progress...

Here's where I was when I discovered I had a problem..

I had mounted everything on the newly constructed feedbelt frame, and discovered the binding, and the belt wouldn't track very good...













So then I took it all apart, took a hammer to things to widen the strut where it narrowed, and then reversed everything so that the fixed end and the sliding bearings were flipped on the frame.. Then I ditched the springs..

The whole thing seems to track way better.. seems to not walk at all anymore, but I won't know for sure until I put power to it... It is also a lot easier/faster to adjust now...






I need a new welding helmet so I can see what the heck I'm doing.... Half my welds wandered off the joint.... Then the switch on the handle was acting up, and I ran out of gas... Perseverance.. not real pretty, but solid and square where it needs to be..

So next I'll cut the infeed and outfeed tables out of 1" MDF, as well as the center underbelt support table, and get those mounted.. Will probably glue some #16 sheet metal on top of them... I also priced out the steel I need to build the main frame, and that is what I'll work on after the feedbelt tables... So far so good...

[ger21]

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.

[LouF]

$15 for shipping is way out of line I agree Mark the guy is crazy..

Lou

[rocketflier]

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Enco usually has a 20% order discount (usually towards $100) or free shipping (smaller orders) depending on the month. Poke google for a bit.

[greenb_60097]

Enco is offering free shipping on any size order this week.

Bg

[rocketflier]

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Hurry! Offer ends Friday, 2/17/12.

[Mountaincraft]

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)..

[Mountaincraft]

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?

[adprinter]

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 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.

[HorridHenry]

Oh wow,you're going to have some fun aligning that chain on each sprocket ain't cha,I mean one sprocket only has to be 1 thread out and its gonna drift the adjoining sprocket/s

[Mountaincraft]

Oh wow,you're going to have some fun aligning that chain on each sprocket ain't cha,I mean one sprocket only has to be 1 thread out and its gonna drift the adjoining sprocket/s

I figured it out, and one sprocket equals .0067 inch of vertical travel, and then that is spread across a minimum of 25" which comes out to .00027" per inch... Add to that that the drum mount on the top end will also be adjustable, and everything is fine tunable with an end wrench or allen wrench...

Furthermore, simply loosening a pair of setscrews on the sprocket and turning the acme screw allows for adjustment without removing the chain to jump a tooth...

If I can get to where I'm precision sanding to the point where 6 thousands across 25" is a problem, I'll be pretty dang excited (How consistent is sandpaper anyways?)... Heck from what I can see, the wood itself changes more than that just between day and night temps... There always seems to be at least a little warping, cupping, twisting going on with temp and humidity changes even with thoroughly dried and planed wood...

They use a very similar method on surface planers....

I'm quite sure that as long as I get the belt tracking issue resolved, I'll be very happy with this things performance for it's intended purposes.. I will have saved a few hundred (or more) dollars over buying one, and it will have custom features included that are simply not available on any retail sander I have seen..

So, one of the two issues I was concerned about has been addressed (how much rotary force was required to lift and lower the table) and has exceeded my expectations, and one remains (belt tracking)..

After that it's all downhill... The top end should be pretty straight forward.. I have pretty much all the materials I need for that already.. And having the CNC to precision cut the parts should make it all go fairly smoothly...

The only remaining design issue I even see is how to extract dust most efficiently without having the fittings in the way and still allow for the quick change drums...... But even that is starting to get nailed down in my head...

[LouF]

Mark, now I know what happen the chain from my old Indian...:stickpoke


Lou

[Mountaincraft]

So, I've designed the lead screw bushings to hold the top end of the lead screws in place..

material around the bushing hole at the end has to be pretty thin.. (.2")... So MDF/hardwood is out..

Worst case, I'll go with aluminum, but I've never machined it yet and really don't want to use any of the scrap I've been accumulating to make gantry supports/transitions for my CNC rig from...

So I looked on line and it seems that Delrin is the hot ticket.. But man, that stuff is pricey... More than aluminum... I don't expect a 'lot' of force to be applied against that edge as most force will be along the sides where I have room to make thicker...

So my question is, how much difference is there between HDPE and Delrin in as far as strength, compression/stretch, wearability (bearing surface), and machinability?

Is it worth wasting my money on a couple cutting boards, or should I bite the bullet on Delrin, Aluminum, or???



For reference, the red part shows a small pocket that will cradle the top of the 1.5" steel tube, while the slot is where a 3/8" bolt and nut will allow adjustability along the length of the steel tube... The round hole is where the 1/2" ACME screw will pass through... The purpose of these bushing blocks is to simply hold the screws vertical..

[TrickyCNC]

Size for Size, I've found Delrin to be cheaper than Ally

I bought a block 4" x 4" x 2" for £4 GBP off of e-bay

Oh, and I have been noticing that a certain poster doesn't have much nice to say about anyones efforts, so I'd take it with a pinch of salt If you think about the alignment of a chain on a pedal bike ... it's not very accurate at all !

Keep up the good work

Rich

[adprinter]

So, I've designed the lead screw bushings to hold the top end of the lead screws in place..

material around the bushing hole at the end has to be pretty thin.. (.2")... So MDF/hardwood is out..

Worst case, I'll go with aluminum, but I've never machined it yet and really don't want to use any of the scrap I've been accumulating to make gantry supports/transitions for my CNC rig from...

So I looked on line and it seems that Delrin is the hot ticket.. But man, that stuff is pricey... More than aluminum... I don't expect a 'lot' of force to be applied against that edge as most force will be along the sides where I have room to make thicker...

So my question is, how much difference is there between HDPE and Delrin in as far as strength, compression/stretch, wearability (bearing surface), and machinability?

Is it worth wasting my money on a couple cutting boards, or should I bite the bullet on Delrin, Aluminum, or???



For reference, the red part shows a small pocket that will cradle the top of the 1.5" steel tube, while the slot is where a 3/8" bolt and nut will allow adjustability along the length of the steel tube... The round hole is where the 1/2" ACME screw will pass through... The purpose of these bushing blocks is to simply hold the screws vertical..

You might try going to a cabinet shop, and pick up a piece of Corian. It machines like wood (sawdust, instead of melted plastic), and it's some pretty strong stuff. Since color shouldn't matter in your application, I'm sure anyone doing a remodeling job with Corian counter tops would probably have some scrap pieces large enough for your use. I mention this, (the color) because it will probably widen your options in finding some.

[adprinter]

Looking good Mark! I will have to get around to doing something similar someday. After a bout in the hospital, and MANY redesigns, and rebuilds, I have finally finished (Successfully) the dust shoe for my CNC router table. I wanted a "Floating Head" type, which can glide over the surface of the table, while allowing the Z axis to move (without the need to lift the extra weight of the dust shoe). What looked good on the drawing board, turned out to be a real challenge to convert into reality! I will post photos probably sometime tomorrow.

[CarveOne]

More good words of encouragement Mark. I'm glad to see that it is working out for you. This one is a bunch of design and build work.

[revwarguy]

Very, very cool, Mountaincraft! There is certainly a lot of good stuff going on here. You have every reason to be proud of it.

One thing I can easily recommend - DO get a dust collector. These things are very hazardous to your lungs! This is not a chip cleanup issue but an insidious invisible lung dust issue!

After getting my drum sander going, there was a couple of times I was lazy and didn't connect up the DC to it (see? I even had one already and was just stupid) and I regretted it for a full day both times!

I even made up the attached sticky label to remind me. If anyone would like one and will promise to post a picture of it in use, I'll mail one to a regular post office address you give me in a PM. I also made some other ones but with different text for my CNC.

[boblon]

Congrats on reaching the proof of concept point, I love those points.
A really nice build and a pleasure to watch.

You've got me thinking of looking at making an add-on to my Delta DS as I always wanted one to those tabletop drum sanders.

Nice job though, congrats.
BobL.