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Old 11-11-2011, 12:05 PM
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Making the mobile base from shopnotes

I just finished making the mobile base from the January issue of Shopnotes. I had casters from an old moving dolly I made years ago that hasn't been used in about as much time so those became donor parts for the mobile base. I am sure it will be way more useful!
My total out the door was a reasonable $22 so it was well worth the effort. Yes it took me a couple of hours, but shop time is valuable to me and so is overcoming obstacles during the build and learning.

I did have some issues upon completion and hopefully someone can help me determine if the two substitutions I made on the fly are causing the problem. The problem is that the two plywood "leaves" separate spontaneously, as if the latch can't hold them together.

1. I used all swivel casters as that is all I had - the plan call for two fixed casters. Would the rotation of the swivel caster cause the separation? (eccentricity of the wheel around its axis allowing more up down movement of the short leaf?)

2. My latch placement wasn't off to one side as shown in the picture. I didn't use as much overlap on my leaves, perhaps only 2-3" and I failed to plan where the narrower section of the leaf fell which led to me having to place the catch at the front edge of the long leaf with the latch on the short leaf directly in front of it.

I had company coming so I had to stop. Should I make a trip to the BORG and pick up a set of fixed casters or do you think remaking the short leaf such that there is an area off to one side as shown to mount the latch?

Thanks in advance!
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Old 11-11-2011, 12:54 PM
jking jking is offline
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The casters you picked won't cause the problem you are having. There a couple of changes I would consider.

1. Two latches on each side of the leafs.
2. Move the latch location as close to the free end of the bottom leaf as possible.
3. You might need to try a different type of latch, also.

If I was building this from scratch, I would make both leafs the same length and as long as possible. They have the latch shown in a bad location. The closer the latch is to the free end of the top leaf, the more load it will have on it. The latch should be located as close to the end of the bottom leaf as possible & the bottom leaf length should be maximized.

You might find it necessary to remake the bottom leaf (or the top, too) to make this design work.
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Old 11-11-2011, 02:02 PM
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Thanks Jking, always appreciate your insight! I figured the latch could hold the force but forgot the fact that its now at the extreme end of a lever. Thanks for pointing that out. I updated the photo. I'll give the longer overlap with one latch a shot before buying anything else Thanks again!

Another thought I had when I saw the article was that the release would be like dropping the machine from 1/8" height, may not me much but for some machines that have more sensitive settings this may cause some issues. I was thinking about using a compression spring centered over a bolt with fender washers maybe in the middle of the leaves/wings. My thought is that it would slow the decent and also aid in re-latching (currently the short wing just drops to the floor). Is there a simple way of figuring out what lb/in I should use? The hole for the bolt between the wings would actually have to be a slot to allow for the up/down movement of the wings.
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Old 11-11-2011, 02:08 PM
toolguy1000 toolguy1000 is offline
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i built that same mobile base using 4 swivel casters i had lying around. the use of 2 fixed casters will make the disengagement and engagement operations go much more smoothly allowing the tool to be positioned more precisely. if you have to use 4 swivel casters, try to get them all pointing their wheels in towards the center of the base. it makes activation a lot easier.

when they separate spontaneously, do they separate with the plywood leaves flipping up or down? i had this problem and remedied it by making the long plywood leaf longer than i thought necessary (this added leverage also makes engaging the base easier and provides more control in the lowering operation).

rather than using that storm door latch, i just created a pivoting brace that pushes the long leaf down and "locks" it in place (the garden gate latch i tried in the pic didn't work out).



just remember that the mobile base is designed to raise the base only a little to provide for mobility. my casters were 2", i think. smaller would have been better for the engagement of the leafs.

ps. jsut saw the above modified drawing. the longer the lower leaf is, the higher it will push the upper (longer) leaf up in the disengaged position. i found beveling the active edge of the lower leaf @ 45* to be very helpful in operating the base. and making the distance between the axles as long as possible will also help the operation of the base (that's one thing my base didn't do, but i was trying to jam the mobile base into an existing, rather crude wood frame tool stand).
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Last edited by toolguy1000; 11-11-2011 at 02:21 PM.
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Old 11-11-2011, 02:55 PM
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Thanks toolguy! Currently they flip down and since there is not enough overlap they can actually come back up with the lower wing over the upper wing! I didn't put enough time into the design, I figured I could just scale it from the drawing... Obviously not experienced enough to have seen each detail in foresight.

I like your use of conduit instead of drill rod... wish I thought of that! I had some concerns over attaching the copper pipe strap to the rod... and the electrical conduit strap had too much gap in it. Then again, the 1/2" drill bit I saw at BORG was over $10 I can only imagine what a 3/4" bit would cost...makes me wish I had picked up one of those cheap HF step drill bits

Thanks for the tip on beveling the edge, makes good sense.

If I get some time tomorrow I will recut the lower wing and reposition the latch and give it another go. Because the tool base (jointer) I am using is enclosed on two sides (front and rear) I may have to build some extension handles to operate the latch and make it easier to reach under the machine to re-engage the wings.
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Old 11-12-2011, 09:29 PM
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The relocation of the latch worked great. I also added a lever to help with pushing the long wing down to reattach into mobile status. Not a bad little project, good value IMHO.
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Old 11-12-2011, 09:51 PM
toolguy1000 toolguy1000 is offline
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it functions very much like a herc-u-lift.


chop........how about a pic or two of the finished unit?
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Old 11-13-2011, 01:08 PM
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Sorry toolguy, didn't have the camera handy yesterday. Rolls around like a dream No spontaneous latch opening, but the lower wing when disenganged drops down and doesn't reconnect unless you get under and pull it up. I think I need to move the casters in more, they are currently centered over the 1/2" rod. As you can see in the last photo, as the caster swivels on its axis, the wheel ends up being outside or behind the rod making the wing tip down.



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Old 11-13-2011, 02:30 PM
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looks good. but if i may suggest something, try this the next time you disengage the base. pull the jointer towards the wheels that are under the shorter of the 2 wings. this should cause the wheels to swivel so that the wheel is now on the inside of the axle of the short wing. then disengage the wings. in the original pic in your opening post, the fixed casters are on the short wing. that's, i believe, to keep the the wheels in a position that prevents the lower wing from dropping upon disengagement, as is happening to you.

also, if that engagement extension ( i did something similar to my base) is attached firmly to the longer wing of the base, the extension need only protrude past the tool base by enough inches to accomodate your foot.

BTW, how do you disengage the storm door latch as it seems to be "covered" by the lower "shelf" of the tool base?
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Old 11-13-2011, 02:55 PM
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Thanks, I will have to give that a try. The latch doesn't have an extension built yet. I am thinking of putting some plywood above and below it and sandwich it with some screws. The extension looks long, but its not really that long and is hidden by the wing of the jointer above.
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