Maslow Home Maslow Community Garden

New Sleds **BETA Testers Needed** Inquire Within

machineimprovements

#41

Another render possibly like this. Then again maybe I’m all wet and my analysis is way off.


#42

Ball bearings are point sources quite different, apples to oranges comparison.
there is FLAT bottomed UHMW trim available. Of course the wider the trim the harder it is to bend into a tight circle. Anyways vast majority are not doing pocket operations, just simple cuts with a 1/4" bit kerf. I cannot recall seeing any projects where a perimeter trim would cause an issue. Even the cell pc case which is about as holy as you can get should work. Of course now that I say this, someone will post a project that might cause an issue and I will have to eat crow. lol.


#43

We’ve done some testing with a wooden version like this. One of the issues we saw was a change in bit angle when negotiating a change. So if we only had single passes cutting out a project, it was fine. But if we were making a sign with multiple sections of missing material, it would “wobble” ever so slightly when advancing across the dips and valleys in the project.

Decreasing depth per pass and using a smaller diameter bit can make this less noticeable, but also add time to the job.

With that said, I still think this design has its use cases and offers a lot of improvements over a fully flat surface.


#44

Many ball bearings arranged on the perimeter would act essentially the same. The point was illustrative not practical. Anything that comes to a limited point of contact is doing to be subject to the same problem. Although it reduces surface contact and one would thing friction as well, MMC’s post above is exactly what I would expect to happen. YMMV


#45

any sled will have issues with missing material that is about 50% size of the sled, for best results one should not have missing material at all, do not remove pieces until the full piece of plywood is cut… I think one test using plywood missing pieces is not very conclusive. more tests need to be done under normal circumstances. (no missing material)


#46

Totally agree with not removing pieces during a cut. Our observations were made on a project that had some carves involved where the material was removed in passes and keeping it wasn’t an option.


#47

Came home to 3 sheets of 1/8" HDPE today!

Still waiting on UHMW.


#48

I would be willing to do some testing if needed.

Thanks ,
Mike


#49

make sure you specify that the UHMW sheet needs to be flat. I’ve bought some in the past that was really wavy. Maybe some Is extruded vs cast? or different grade? not sure.


#50

Thanks for the tip! What we ordered recently was just described as “sheet”, hopefully we don’t run into any issues. Will definitely be making sure we provide more detail specs when we go into production now.


#51

image
I’d like to see HDPE/UHMW nodes all over the bottom of the sled similar to those on an inline hockey puck.


#52

Just a quick idea after reading this thread.
How about a 1-2" edged plywood ring cut from sled thickness plywood on the Maslow that would fit around the perimeter of the sled. This ring would be attached to your plastic of choice with a hole in the middle for the router bit. Either hold down clamps, the weight of the sled or 2-3 wood screws through ring and sled to hold it in place. Basically a plastic bottomed cradle that the sled would sit in. The cradle could be replaced/exchanged quickly as you could fabricate many of these before hand. Either replace the plastic after removal and re-use the ring or discard entire unit.


#53

We haven’t forgotten about everyone!

Still waiting on the shipment with UHMW sheets to arrive before we get started.

If we can agree on some initial designs as a group, I’ll make sure those get cut first.

Would everyone like to test the plastic sheets first and then move on to adding metal sleds?
Or does everyone want to do metal sleds with the plastic bottom layers from the start?

I’ll be opening a jotform sign up form this week for anyone that wants to apply for the beta so I can keep everything organized a little better. Be on the lookout for a reply to this thread with a link.


#54

I think it makes sense to start with the metal+plasic combination,
wood+weights+plastic is not going to be any better (it may not be any worse, but
will not be any better)

I think shipping the sled with pre drilled (possibly pre-tapped or countersunk
as appropriate) holes will be a big win. Please drill for both linkage kits and
the ring

for the wood kit, this is 4 holes 9" on center in a square centered on the bit
(4.5" from the bit along an X centered on the bit)

For the metal kit, it gets a little tricker as it needs a hole 6.75 and 8.25" up
from the the bit. either you will need to have the sled be a bit of a lollypop
shape to accomodate this, or we will need to have a couple holes within the
range of the bit and then some sort of bracket (possibly a carved up 2x4) to be
able to hold the center support from the kit.

I know you wanted to keep the disk down to 12" to fit in a large flat-rate box,
so that could allow you to do the lollypop idea (the stick would go right into
the corner, possibly with the outer hole being a notch for positioning, and a
second hole for anchoring things)

David Lang


#55

Finally got tracking information on the UHMW and Nylon sheets!

It’s looking like it will arrive on Saturday, so I’m hoping to tackle these sleds next week.

Is everyone in agreement that 1/8" is the ideal thickness for the metal piece? The lower plate will be 1/8" thick as well.


#56

no one every agrees on anything here. lol. really depends on size. if doing 16" or larger 1/8" will give you around 10 lbs, if doing smaller to fit in a smaller box a 12" circle that is 1/4" thick will weigh about the same. Use the right thickness to have it weigh 10 lbs or more is my advice.


#57

Sound advice!

We will be at the standard 18" for the first round of tests, so 1/8" it is.


#58

the ideal thickness is whatever is strong enough and about the right weight :slight_smile:

David Lang


#59

Working on files for test sleds this week.

Here are a couple things I’d like some feedback on.

  1. Threaded standoffs for ring kit brackets or countersunk holes and use bolts and nuts to attach?
  2. Outer ring of lower plate sit flush with sled or overlap edge? I could see benefit in overlapping to prevent the metal sled from accidentally coming in contact with build material.
  3. 12", 15", or 18" diameter? I’m aware of shipping challenges with larger dimensions, but don’t want functionality to suffer because of it. Plus with them just being flat discs, we could probably ship in a large padded envelope.
  4. Router models to support. I know the popular ones are the Ridgid R22002 and the Bosch POF 1200, are there others that should be accommodated?

Thanks,
Chris


#60

Here are a couple things I’d like some feedback on.

  1. Threaded standoffs for ring kit brackets or countersunk holes and use bolts and nuts to attach?

whatever is most rigid. Any flex in these standoffs will translate into position
errors (in some locations, at a 2:1 ratio, 1mm of standoff flex = 2mm of
position error)

I am concerned that the standoffs will flex in either case and you will end up
having to go to something with gussets.

  1. Outer ring of lower plate sit flush with sled or overlap edge? I could see benefit in overlapping to prevent the metal sled from accidentally coming in contact with build material.

the sled doesn’t tip, so I don’t think there is a need for overlap.

  1. 12", 15", or 18" diameter? I’m aware of shipping challenges with larger
    dimensions, but don’t want functionality to suffer because of it. Plus with
    them just being flat discs, we could probably ship in a large padded envelope.

as a general rule, larger is better (assuming the same weight). The standoffs
could be a problem with the envelope.

  1. Router models to support. I know the popular ones are the Ridgid R22002 and the Bosch POF 1200, are there others that should be accommodated?

since you are going with a separate Z axis rather than relying on something in
the router, see if you can make the bracket accomodate things from a 50mm
spindle like:
https://www.aliexpress.com/item/500W-CNC-Spindle-Motor-ER11-Air-Cooled-Spindle-Adjustable-Power-Supply-52MM-Clamps-ER11-Collet-Chuck/32864211347.html
to the r2202 which is 3 5/8" diameter IIRC

outside the US, it’s hard to find a router with a cylindrical motor, everything
that’s readily available has a plastic molded case similar to this (but many
with the handles molded in to the motor)

working aound those handles is a problem for the linkage kit you are using
(that’s one of the advantages of the top mount kit),

David Lang