Thread: Hand sander with dust extraction

Now I know that these gizmos can be purchased for not much but I wanted a project to help me learn to improve my 3D printing CAD software skills and if the final product is not vaguely useful I won't be interested in finishing it. Actually printing the components which have to fit together neatly is a major second challenge.

So this was the plan I came up with.
The perforated base is 198 x 70 to fit a standard type of Abranet sheets.
Attachment 514190 Attachment 514191

The idea is to line the perforated base with hook and loop material and to have multiple inter-changeable bases that should reduce the number of times the abrasive is put on and removed from the hook and loop surface. So you might have say 4 or 5 bases with different grits and just swap the bases around until the abrasive has had it and only then change the abrasive on that base. Could even have colour coded bases for different grits?

In this business it's rare to design and print and it all goes together first time like clockwork. The vagaries of the materials and the printing process will not always generale sub-mm perfect components that all fit together as desired. So prototype's are usually required.

So I started by printing Prototype 1.
I'm using a roll of cheap PLAF (A mix of PLA and ABS) printer filament material which cost me $10 on special so I'm not fussed about the cost of printing prototypes with it.
The final product (especially the base) might be printed in PETG as its stronger and more flexible than PLA - you will see why shortly.

As well as fit, this also gave me a chance to test out ergonomics before I start sticking loop and hook material onto it.
1 in the photo below is the first prototype I printed, the egg handle did not feel quite right so I rotated the egg and sloped the egg down at the front
Also i dropped the height at the front so the slope is a bit steeper and this is shown in prototype 2.
Prototypes.jpg
Prototype 1 was printed with 0.2mm line spacing while prototype 2 was with 0.1mm spacing so it took lot longer (37 hours!) to print!.
I go and do something else while its printing.

The remainder of the parts look like this
Protype2.jpg
I added a sloped edge to the inside of the RHS of the base for the RHS of the top to wedge under and the clip/tab thing on the LHS of the base holds the LHS of the top onto the base. This works much better than I thought it would.

The spigot for the vacuum cleaner took a couple of goes to get right, first time I printed the collar too large and second time the ID was still too small for my vac. So 3rd time lucky.

The base I had to print twice because I printed it too narrow.
So this is what it looks like assembled so far.
Protype2assemb.jpg
Now I knew that little tab thing at the front of the base was going to eventually snap off (in fact it did about 5 minutes after I took the photo) and this is one reason for eventually printing the base out of PETG. The spigot is just sitting there at the moment - haven't sorted out how to hold it there more permanently - I could glue it in , or use small screws or maybe even a bayonet fit.

To print the top with the embedded egg handle is pretty tricky. The top and egg could be printed separately and then glued together but I wanted a really strong bond so I had to print them together and this means right way up and so supports need to be printed to create the internal cavity otherwise it would collapse while printing across the void. The slicer programs which turns the STL file into gcode takes care of all this

However te result is the underneath of the top prints like this.
That large perforated block in the middle of the cavity is loosely bonded to the rest and has to be removed and that plastic gets chucked out.
Protype2support1.jpg Protype2support2.jpg
The support plastic weighs 34g compared to the weight of the top including the egg handle which weighs 78g.
The value of plastic wasted by this process work's out to be a whole ~34c so it's no different to most timber wastage.

Here's view from underneath
I'm going eventually line the base with 6mm thick neoprene tape before I add the hoop and loop material.
The some of the holes will be punched through the two materials.
Protype2under.jpg

All up I've used <$3.50 worth of plastic to get this far. When I print out the final product I'll be using plastic filament material that costs 3-4x more than this budget level PLA but even so the cost to print one unit should only be ~$6.50 and extra bases should cost around $2 each.

I learned a fair bit doing this - the design/plans are almost fully parameterised - so can easily change height, lengths widths, wall thicknesses, diameters of egg ends etc with little effort and it all (mostly) looks after itself.
It fair got my old brain cells working, translating between code and additive and subtractive 3D structures, plus with a bit of program loop control, and minor trigonometry that I used to use a lot at work.

The current program has about 200 lines of code and once I get it finalised I'll put the plans on Thingiverse.