CNC Lathe making chips and choosing a video editor

I guess I should have chosen a curvy part instead of this boring one… maybe the next time.

Now some words about my search for a decent linux video editor. I did my previous video using OpenShot; It was a bit crashy and I really don’t like the way it handles titles. So after checking some reviews and doing some tests, I finally settle on Kdenlive, which is really nice.

Homing switches for the mill

My cnc mill itsn’t ready yet, but I hope it will be soon so I’ve been starting to learn a bit of gcode. Meanwhile here are my homing switches.

My approach here it’s very similar to the homing switches I did for the lathe some time ago. For X and Y axis I’d use the same type of micro optical switches; maybe RPI-131 from Rohm , maybe ee_sx1103 from Omron, not sure. For the Z axis I’d use a more typical H21A2 from Fairchild. Of course optical switches are only advisable when you can protect them from chips and debris.

home_swt_01 home_swt_02 home_swt_04home_swt_04After intalling and testing you should configure homing switch location and travel range for every axis (a trial-error process). Now I know the cutting envelope of my machine is 206 x 162 x 172 mm (8.1 x 6.37 x 6.77 inches).

Regarding to the nice spindle distribution box: I learn that doing deep pocket milling by hand in polyamide it’s a very unpleasant task (at least this 48x66x21 mm pocket).

home_swt_05Pleas note this is the only one polyamide part on the mill; other plastic parts are delrin made.

No THAT Monster

Here I will share some thoughts regarding Sherline milling machines.

First, Sherline mills are great machines.

  • Almost unbeatable price/quality.
  • Compact and lightweight.
  • Lots of accessories and even a cnc kit.

Second, these are nice machines, but not perfect. It seems most users are happy with their Sherline’s, but pointing most obvious weaknesses it’s healthy.

  • Weak column. A 10mm thicker column would be great.
  • Short throat. You need two spacer blocks on the headstock to be able to use the full Y travel.
  • No provision for delrin nuts.
  • Annoying motor location (inherited from the lathe, obviously).
  • No leadscrew/ways protection out of the box.
  • Gib system (it seems I’m the only one that hate the gib system, so ignore this).

Third. I think the “monster mill” philosophy it’s wrong. Basically, and this is my personal opinion, extending every axis and changing to ballscrews it’s not worth nor advisable. May be extending X axis and putting to ballscrew on Z axis, but a full monster mill it’s really ugly to me. I should also say that I prefer model  5000 over 2000, but I don’t think 2000 model be a bad deal.

So this:

column-headstock_2And still a lot of work ahead.

UPDATE: We are in 2015 and Sherline has a lot of new products and enhacements. Now they have a nice ways cover and a big spacer to give more throat.

Leadscrew/Ways Cover

A cover for the Sherline mill it’s a must if you wish your mill last. This is the typical “accordion” cover, a very practical solution actually:

Now here’s the leather/delrin cover I actually use. Tough not pretty, a good thing about it is that it allows easy access to X axis lock screw (something that I use a lot).

leather_cover-01leather_cover-02And here’s the new cover for my modified Sherline cnc mill:

sherline leadscrew covercnc_cover-02A bit radical but effective and easy to clean (I hope). I will comment the whole design once completed.

Now, the next things I need to tackle will be anti-backlash nuts and column mount.

Big fly cutter

Here is a very simple but highly useful accessory I made from a 13x13x40 mm block and a broken end mill.

flycutter-01 flycutter-02And here’s a 76x140mm flated surface.

flycutter-03There was some vibration due to the unbalanced rotating mass, something that I fix later adding a simple counterweight. And of course I took advantage of a not-perfectly trammed head to get a nice finish (about 15um less in the middle, not bad).

Finally a picture showing how useful is the side plate.

flycutter-04

UPDATE (01/09/13)

In the last working round I just note some upset behavior related to, I guess, thermal expansion. The DOC can increase, easily, 0.02mm after a couple of millimiters of feed. You can learn to deal with this, but now I think that a bigger mass cutting bit it’s a better idea (of course this doesn’t matter if you use coolant). Anyway, no matter what flycutter you use, I think a double finishing pass it’s always a good idea (0.03 and then 0.02 mm for example).

CNC lathe limit switch and other things

I’ve been busy so there’s nothing new to show at the moment (this will change soon).  So in the meanwhile here are some old pics of the ongoing manual lathe to cnc convertion. I start this project with used Sherline parts (a not well cared bed, headstock and tailstock I bought on ebay).

– Using the manual lathe to drill to motor mount holes on the bed. I use some custom made aluminum blocks to raise the bed to the required height.

– Adapting the leadscrew thrust.

– A custom made nut to fix preload nut (I think this is better than glue). Please note that I bought cnc motor mounts only, not the full upgrade kit, so I must adapt the leadscrew also (this was a bit tricky).

– Making a limit sensor. Sure, this is not required, but it’s handy and nice to have. I use delrin and some floppy drive sensors.

– Limit flag and mount for the Z axis.

– A better flag. I hate this way of cutting metal sheet, but didn’t had the table saw at this point. I use scrap sheet metal from a pc case.

– Full assembly  of the limit sensor.

That is. May be a fixed sensor on the rear would be a better idea, but nevertheless this limit sensor works very nice. I must admit homing the lathe has something hipnotic.

Going Horizontal

Today I finished a very simple accesory that turns the standard sherline mill into an horizontal mill, within seconds. It’s designed so it doesn’t get in the way of the table, so it can remain installed.

I don’t know why I didn’t figured this before… so nice. Will upload drawings in a week or so.

Drawings

This isn’t exactly the design I build, as I didn’t had a plate stock of the required size. This version cover all the riser block side.

Update (Jan 2014): By the time I’ve used this accessory I’ve found it has a design flaw; it flex more than expected (It had been very, very useful, tough). So now I think a 3/4″ plate should have been better.