[fuper]

Thank you for the kind words and critiques askjerry!

I will follow your recommendation on the brush. I had it grab the brush the other day and I see what you are saying! Funny I was reading in the Sherline book and I could've sworn the author said use a brush to remove chips.

Overall the build went well. I think it's fairly accurate and I think the oversized rails at 16mm all attached to a 1/2" chunk of mic6 plate helped out. I'm still getting my toes wet running simple gcode and testing the limits of the machine. I should of made the design x & y bigger as m z-axis is larger than I would of liked.

Regarding the threaded rods: Something always felt off about how I did it but I wasn't sure what. I think I understand what you are saying. Thrust bearings on the non stepper side with with two nuts on either side tightened down? When you say retainer do you mean the two nuts?

It's a good idea. I had a bunch of nuts come with the rods I got from ebay and never thought of using them that way! The collars I am using never gave a tight fit in the axial direction, so the backlash was always bugging me. Can't wait to go home in fact

I plan on redoing the main axis supports as the first useful part to be made out of this design. Now that I can mill nice holes, building these parts to fit the bearings and what not should be much easier.

Thank you.

[fuper]

Hi Hazardouschurch -

The pillow blocks are "OK". I doubled them up and it's actually decent for what you are paying. Are they as good as hiwin rails or something? No but for the price they are decent enough. I have only just started milling with this machine and am still learning the whole CNC process but the end cuts are very nice, no chatter etc. I think the 16mm rail thickness combined with the short travel, 12" makes it sturdy. Also the entire thing is mounted on a single monolithic piece of plate. Not sure if that is a factor or not but I feel it likely is.

Shane

[fuper]

Yes this turned out to be the trick. Luckly I was able to double them up without redoing a bunch of parts but I lost a few inches of travel and it's kind of a hack but it did work!

[fuper]

Here are a few notes I will share for people just starting out - hopefully they are useful. When I started out I had never worked with metal before so I learned by making a ton of mistakes, asking for help, reading and I still have a ton to learn. Hopefully this will be helpful to someone like myself.


1) The unsupported linear rails [on my machine ,16mm case hardened steel from ebay] will deflect and are not easy to mount. I suggest using supported rails. The rod sits on an aluminum extrusion throughout it's entire length. There rod is drilled and tapped and bolted from the bottom to the extrusion. I purchased two of these for a newer version of my z-axis. The resulting structure is definitely more stiff.

These parts are easier to mount as well. They come pre-drilled and you just bolt them to your surface. With the unsupported rods, they are only attached at two points on either end. This is not as rigid and also requires you to be able to make a nice 16mm wide hole which is not as easy as it sounds if you don't have access to a suitable sized mill or lathe. You can purchase 16mm mounting brackets, which I did. These are great but, again, are not as strong. They are however easy to mount.

Note: I used a scrap piece of plastic to prototype the new z-axis for the base plate that the rails are mounted two. It's 1/2 HDPE and this feels stronger than my older version which was made from aluminum. My old version used 2.5" x 0.5" bar stock. You can see pictures since it's not an apple to apple comparison.

2) Bolt your machine down to your work table. I noticed a lot of vibration on deeper cuts. I clamped the router down to my work table temporarily and the vibration ceased and the machine cut better. I didn't factor mounting my machine in this way and will now go back and drill out suitably sized mounting holes. It's not likely to be a big problem in your design in case you forget but it's something you should anticipate if you are just starting out.

3) Pay attention on how you mount your acme rods. the rods should be able to rotate easily by hand [kind of obvious I guess] but should not have any movement axially. Make sure you have lock collars or some other means of clamping to prevent axial movements in either direction. I cannot stress this enough. If you don't your machine will be springy when it cuts into anything. I spent this weekend on and off as time allowed addressing this issue.

Make sure your acme rods are really straight. I purchased 3' of used acme rods off ebay not knowing anything. After testing the movement of my router a bit I realized the stepper motors sounded like they were dealing with excess stress at some points. My father in law was with me and he is a retired mechanical engineer. We removed all the acme rods and laid them out on a surface plate. All the rods were bent, one of them fairly obvious and this was causing the problem.

4) Surface plate and a height gauge. Purchase them. You can pick up a surface plate from craigslist or ebay or from a discount tool catalog like Enco. They are not that expensive, although shipping is. Expect to spend at least a hundred bucks. Shipping will be more than the plate so if you can get one locally great. Get a right angle plate. These are pretty cheap too. You'll need a scribe and center punch. You can get a set from grizzly [never used them but just an idea] for $10.00 bucks. Armed with these you have the tools to layout everything on your material. I cannot stress that these are really important.

5) Center drill set. Pick up a set of center drills. These are short stubby little drill bits used to start drilling accurate holes. They don't flex. They are inexpensive. Without them you will not be able to drill accurate holes. Read and watch videos on how to use them.

I strongly suggest if you have never worked with metal before, like me, practice laying out and drilling a bunch of holes on scrap metal. You will quickly realize that if the holes don't align up exactly the pieces won't bolt together correctly. It's not wood and it's not as forgiving.

Also as a side note - If you are bolting two pieces of metal together, one piece has a clearance hole [meaning a hole large enough for the bolt to pass through] and the other is drilled smaller so it can be tapped. The compressive force of the bolt holds the two pieces together. If you tap both pieces they won't be strong and won't bolt together properly.

6) Tapping - practice it. It's harder than it looks [for me anyway] and you will break taps. For instance I have never tapped #4-40 aluminum without breaking the tap. Hopefully you are better at it than me! I use #10-32 everywhere and I've not broken a tap in a year on this size.

7) Use socket cap screws. They are superior in every way to regular machine screws except in their price. When testing the assembly I used machine screws as they are inexpensive. They are however easy to strip so don't go hercules and try to tighten them down as much as possible. You will strip them. When you are assembling everything use socket cap screws. They hold tighter, are much harder to strip [I've never stripped one] and are better made. Buy them by the box to avoid paying crazy per-piece prices.

8) Cutting hardened rod - if you are using linear rod, likely it's case hardened which means they heat treated it in a special way to make the outer part of the rod really hard. There is a whole bunch of reading you can do on this topic, suffice to say you will not be able to cut it at all with a hacksaw. Go to home depot or lowes and buy an electric cut off tool. These are pretty cheap. Buy a few cutting wheels. Put the thing in a vise, wear leather gloves and cover your face, I got a full plastic face shield from home depot for like $15 bucks. This thing throws mean sparks that will scorch surfaces easily. They are scary tools if you have never used one. Since I'm in an apartment I had to do all my cutting outside. I had my vise attached to a piece of MDF and just cutting a few rods blackened the cement pavement. However the result is great. These wheels cut through hardened rod like butter. Pretty amazing.

9) Hacksaw - if you have a chop saw or a bandsaw, great! If not, like me, you use a hacksaw. Buy one, throw away the blade and pick up american made cutting blades. You will be glad you did. Read up on this, because you want a certain number of cutting teeth for the type of material you are cutting. In general american made cutting tools are vastly superior to imports. I never buy drill bits that are made in china. They dull out too quickly. Spend the money and get the good stuff. I would trust German or Japanese bits as well.

Thats it for now. Hopefully this is helpful to people like myself.