THUMLER’s T No. 100 back online (after lid wore through)

My rock tumbler (THUMLER’s Model T No. 100)  broke down when the lid wore through. This thing is a 3lb capacity beginner model I picked up on ebay.

Today I was able to make a lid for it (so if you need a lid for yours feel free to contact me).

I made a new lid out of some hard cutting board material on my CNC mill. I think these lids are better because they are thicker and are more robust material.

I did a run around the perimeter to make sure it was the same thickness as the original part on the edge. But the rest of the lid is thicker so it should last longer.

CNC Meetup

When: Tuesday August 2nd, 6-7pm
Where: Atomic Rooster Pub, 303 Bank

We can have a follow up at ModLab on Wednesday 7pm (2 Daly, ask for Artengine at front desk).

Proposed agenda:
6-6:10pm: Social
6:10-6:50: Round table (everyone can tell about their projects and what challenges they are facing)
6:50+: We can all reflect on the issues and see who has answers.
Let me know by tomorrow morning if you’re coming so I can book a table.
If that time slot doesn’t work, let me know and I’ll make the next one in a different time slot. Perhaps I can alternate between a couple of timeslots.

 

A-Axis

a-axis

When using an A-Axis I was thinking that I could mount the work piece in two ways. I could have a chuck at one end and a flat plate at the other.

The flat plate would allow me to bolt stuff to it. I guess if it has the right hole pattern it should be easy to make pulleys. I could cut the bore and rough the outside using a 2.5D method. I could add the mounting holes that match the mounting plate on the A-Axis and then finish the pulley or gear on the A-Axis.

I could also mount odd sized pieces with the plate.

I suppose this plate could be made of 1/2″ thick aluminum? I could drill and tap the hole to match the threaded rod that I’m using as the main shaft of my A-Axis assembly.

Does anybody have a 1/2-20 tap?

Nema 17 CNC kit running!

relay

I got this thing running finally.

The documentation was a little poor but after a couple rounds of correspondence with the supplier in China I think I have everything in order.

On thing I really like about it is that it has a little spindle relay.

It appears to be 5A, 120V so that could work with a Dremel.

An ohm meter placed across terminals 1 and 3 on the right seems to vary between infinity and 0 when I click the spindle control in Mach 3 so that’s promising.

Lead/Ball screws, couplers and ball bearings for small CNC

Here are my candidates so far:

Lead Screw

98935A817 3/8-12 lead screw 36″ 2G (McMaster)

This is $5.00 but that’s at McMaster which I think is useless as they wont ship to individuals in Canada. Their competitors are Reid Supply Company, FastenalW.W. Grainger and Manhattan Supply Company (MSC) but I wonder if this can be found locally.

A quick Web search found a supplier in USA.

Ball Bearings

I’m supposing we need a ball bearing with a 3/8″ inside diameter. VBX has them 10 for $24.95 or $2.95 each. In fact, I see a lot of 3/8 inside diameter bearings at different prices. I don’t know the differences yet.

Nuts

3/8-12 Delrin AF nuts. I found them on ebay which looks great. They are about 5.00 each plus shipping.

Couplers

I’m still working on that. The Nema 17 motors I got in China have shafts that measure around 5mm. 3/8″ is about 9.525″.

1/2-10 sized rod and nut might also be worth trying.

Body for a small CNC

I’ve been looking at the Zen which is made of HD Polyethylene. I’m not sure how rigid that thing is but the idea seems inexpensive. Plus the parts can easily be made on one of my other mills.

Another concept is the wooden box idea such as the makerbot or mantis. It could be bulky but it might also add a lot of structure and rigidity and still be affordable.

It might be difficult to work inside a box with a CNC as well.

One way of the other, I came across this version of the mantis.

It uses a box for it’s entire structure.

This could be very favorable for portability.

Also, if it were fitted with a door in the front, this could be a cool solution for dust and noise control.

To make it even more interesting you can mount the electrical to the box easily.

I think if this were fitted with some sort of vacuum, it would be a great small machine.

The box could be MDF and the door acrylic.

Even if most of the box was removable for when you want the machine to be more open.

Portable, quiet, clean and affordable.

Linear Bearings for small CNC

I was just looking at the Zen 12×12″ CNC which is made of Polyethylene, just like my big red colored mill.

This machine uses 16mm linear bearings on the X and Y axis and 12mm bearings on the Z axis.

So that’s:

4-16mm guide rails
8-16mm linear bearings
2-12mm guide rails
4-12mm linear barings

The linear bearing cost is easy. 4-12mm is $19.95. 8-16mm is $39.90. So the bearings are $59.85. I’m a little confused why they list two kinds of 16mm bearings and one is twice as expensive as the other.

The guide rails are a bit trickier to choose since they need to be longer than the travel. The 16mm x 60″ rod is $39.95. I suppose this could be sliced into 4-15″ segments.

The 12mm x 13″ rod is $4.95. That can probably be sliced to create the Z axis rails.

So if the above is right, that comes to $104.75. My only concern is that the 15″ rails for the X and Y axis could be short. This only allows 3″ for the the space taken by the linear bearings. That’s assuming the guide rails can be mounted flush which would probably require drilling into their ends. I don’t have tools for that (unless I can figure out how to do that accurately with my drill press).

I just noticed that the Zen is 18x18x14″. That means there is an extra 6″ over and above the 12″ travel. So if I take enough off th 60″ guide rail for one 12″ axis, that leaves only 24″ left for the other axis. So if I split th remaining, that just leaves 12″ guide rails. If we still need 6″ of extra, then there’s only enough left for a 6″ cutting area. So we’d only get a 12×6″ cutting area.

If we want the machine to be 12×9″ or 12×8″ we’d need more guide rail. If we add a 14mm x 30″ at $24.95, that boosts th cost up to $129.70.  But with the 30″ rod we can get a 12×9″ machine. Plus we have 24″ of 14mm rod left over.

But this begs the question of why we are using the 12mm hardware on the Z axis. We could just convert the 12mm bearings to 14mm (same price) and use the left over 14mm rod on the Z axis. We can then drop the 12mm rod (which was only $4.95). So that’s $124.75 if everything is 14mm.

 

 

 

First CNC Aluminum Part

cnc aluminum!

With the help of my friends I was able to make my first part. This part is a mounting bracket for a generator for a human powered project.

Took a while but there is a learning curve.

It turns out the most appropriate endmill I had on-hand was a 1/8th, 3 flute carbide. I was using a 4 flute of a different brand that I bought bulk. They don’t like aluminum. The flutes are close together and the viscosity and surface tension of aluminum get’s busy with it.

With the speed override of Mach 3 I was able to get some control over cutting speed. Below 10ipm it was easy to adjust it finely. But the next step over 10ipm was 20ipm which was a bit much.

The other thing I did was to use the vacuum to keep the area clean. It’s easy to blow the aluminum away as as well but I think I’d eventually get dizzy. 🙂

endmill broke!

There were lots of delays. At one point (as you can see at the right), I noticed that the endmill was not aligned with the spindle. 🙂 Actually, I broke about 5 or more endmills during this. I broke about 3 cutting acrylic yesterday as well. So I’m getting a little bit of endmill anxiety.

My vacuum assembly worked well but because I kept breaking endmills I had to keep removing it so I operated without it. Next time I make the vacuum holder I’ll keep that in mind.

Serious look at dust: A Cyclone?

cyclone

As you can see by the look of my vacuum, it’s time to look at dust collection a bit more seriously.

I think a cyclone style system is an idea.

I also need a quieter vacuum.

I think it could be made into a workbench and be based on a standard plastic pail of some sort.

I’ll put that stuff on the drawing board. Anybody have one already?

Endmill supply

In the past 24h or so I broke about 5 endmills. I also learned that I need more 2 flute endmills.

I bought a pile of 4 flute on ebay. Here’s an example. I will search for some deals on 2 flute. They seem much less common.

Phlatboyz plugin “tab”

phlatboys tab

Here is a default tab from Phlatboyz plugin for Google Sketchup. Here I’m cutting 1/4 inch aluminum with a 1/8th inch endmill. The default tab is 1/4″. I’m supposing I need to make it wider since it seems to be all used up by the endmill. It looks like it is measured from the “outside of the endmill” rather than the “inside”.

I have been meaning to figure out how to do 2.5D with MeshCAM. Perhaps that’s worth doing instead of worrying about the phlat tabs.

What are these holes on linear bearing blocks

I was looking at the linear bearings on my mill the other day.

What are these holes on the bearing blocks? Are they some adjustment or fastener for the linear bearings?

Could it be to add lubrication?

I’m just curious.

First try at Aluminum with CNC mill

endmill

I took a job out of my queue that required aluminum today. The mill worked well but I had the feed rate wrong or something else was wrong.

As you can see by the first part of the video, I ran the g-code with the mill zeroed a couple of inches away from the workpiece so I could make sure I was away from the clamps and everything was okay.

The job started okay. I seemed to have good rates for the hole drilling.

But when it came to some longer cuts, it seemed to strain. I was taking off 1/64th inch per pass which I figure is small so perhaps I was going too fast. I threw some water onto the cutting area to see what would happen. I had to cut the feed rate right down and it still eventually started to strain.

In fact, I reached a point where it wasn’t cutting at all.

I looked at the endmill after finally stalling the mill. It was gummed up with aluminum. I’m supposing it melted the aluminum.

Coaster test

I finally got the spindle controller going for my Chinese mill.

I did a test run to make a coaster for a bottle of Tuborg I had in the fridge.

The mill ran very nicely. But the job was disastrous.

1) I was cutting to aggressively so the workpiece lifted up.
2) The plastic kept forming into a ball on the endmill and interfering with the work.
3) Balls of plastic were accumulating on the endmill and flinging off.
4) I think the workpiece moved.
5) I broke two endmills because of stuff that’s so dumb I don’t want to say.