First off; my CNC Mini Mill This started life as a $58 Delta drill press
The first conversion of the drill press the build photos are not avail so just the upgrade will be seen here; 2 views of the early conversion
The machine was somewhat usefull in the config seen; but had some limitations in the amount that could be cut; the drill style chuck would come off the spindle taper; usually at the worst possible time; so a new and better spindle was developed
Here are the bearings used in the drill press spindle conversion; the blue lines is were the old spindle was cut so I could use the splines; 2 ball races for spindle rotation/location and 1 needle roller for side loads; lower photo is
the original design and the new better version using Niken collets
So we have an improved spindle for the converted drill press; but it still had limitations; next was a total re-design of the package
I tried to use as many of the old parts as possible to keep the cost of the conversion down
So onto the final design
We will need a much better base; so a 1" thick mild steel plate was ground both side for the base plate; 3 riser blocks needed to be added for clearance for the Y axis leadscrew; mounted to the risers are 2 RSR15 THK linear slides and 1 RSR15W on the right side
Then a 1/2" thick ground plate is screwed to the RSR slide blocks to form the base for the X axis
THe rails are once again THK; but SR25 this time; the ball screw is 0.375" diameter and has a 0.200" lead; with 2 nuts it has been adjusted for zero backlash; stepper is a Compumoter 57-83 200 steps/rev unit; driven by a Zeta4 drive set for 2000 steps
So now we need a Z axis support; here is what I used; it was scrap; nice thing from a strengh point of view is it's hardend Stainless Steel; but thats bad when you need to tap holes; I had to re-grind the 5mm tap after almost every hole
I used a Kerk lead screw for the Z axis; I still have reservations about the plastic nut; but it really is anti-backlash 0.400" lead
The rails are 2 THK 25mm TBA slides and 1 SR25mm slide; there was a difference in height; grinding solved that
The vertical support shield to the base with 4 x 3/8" grade 8 cap heads
So now we need a table and a Y axis screw for the project
Here is the 3/4" thick Aluminum table; 6mm caps hold it to the SR25 blocks; a short section of alum angle holds the X axis ball nut carrier; also seen is the Z axis nut carrier and the Y axis stepper and a bracket for the stepper mount and belt guard
Here is a close up of the Y axis leadscrew; once again anti-backlash; supported both ends; the nut carrier is split to allow even clamping as per Universal Leadscrew Inc recomendations
The Z axis stepper is added to mounts made from 2 x 2 and 3 x 2 alum angle
Stepper ratio is 4-1 on Z and the Y is 2-1
Drive motor for the spindle is a brushed 12Vdc unit originally made for starting model aircraft; it has very good power and can run on 30.5Vdc (but for how long; is the big question)
Here is a close-up of the spindle pulley and motor pulley; actually it's at speed (5000rpm)
Here is the Z axis Kerk 4 start screw that will control the vertical movement; the 3/4" thck Aluminum plate is added for the head to be mounted and the head is now mounted; the converted A/C starter is also mounted but still needs a pulley; the Kerk is supported at the bottom but the bearing setup for controling play up and down still is needed
So to remove the downforces on the plastic nut on Z axis i decided to add a counter weigth; here is the finished C/W assembly; the block is 17lb's and the cable rides on custom brass pulleys with 5mm bearings to reduce friction
This is the Y axis and the hard X axis way covers; the X axis cover will also be a nice tool holder table or just a nice table extension; below is thesliding stainless steel X cover
Here are the X axis home (bottom of the shot) and the X axis limit; I will have the software limits active too; there is a similar switch for the other direction mounted to the plate near the stepper
The Y axis limit and home; a combination ramp takes care of both; the ramp is 10mm from home to limit; just behind is the +direction limit ramp; the + limit switch is actually about 5" away at this point
best viewed at 1024 res
So finally it's ready enough for a cut; the table needs to be machined for the correct alignment of jobs
1/4" cutter 0.008 cut at 300mm/min (sorry for mixing metric and Imperial)
Table is now finished; added fixture hold down screw points and dowel location points
The coolant groove is now done plus my toolmakers vice hold down screws added; this will be the normal 3 axis config for this machine; remember there is a 4th axis which needs a couple of mods for it to be fitted also; the vice will be removed for the 4th to be added; the vice will not be needed when the other fixtures I'll make are in use also
I also added another chip barrier; this one overlaps the SS cover and the Hard/table extention X cover; should stop all chips and most dust from the slides/ball screw; there is a similar barrier on the back of the table
The machine sure needs a name plate; so here is one it made for itself
3D conture cut at 458mm/min with a 1/16th ball 4 flute @10,000 rpm
Heres a stop action photo of the new mill in the process of making an Imperial Japanese Navy Heavy Cruiser Propeller (Takao class) in 1/200th scale
I made a simple jig and cut the other side
So we now add the 4th axis; it bolts directly to the table and is driven by a Zeta4 drive again; the stepper is 300oz/in with a 3-1 reduction
So I found a need for a high speed spindle; which means I now have to build one
Lets get started
First shot is the new high speed spindle mount; the Aluminum block carries both the main adapter which fits in place of the normal spindle
Just about complete and test fitted into the head casting; as you can see I just move 50mm over from the original center of spindle and I'm zero'ed
So why did I need a high speed small spindle like this?
Well for a run of these; it's a 37mm gun as used on the JU87Stuka divebomber
With over 100 to make it seemed worth while
So I do hope you enjoyed reading this as much as i did building it
Next will be a build of the bigger Gantry mill
Thanks for your time; I hope it inspires you to make something too
Steve
Motor mount off the spindle housing; the slots are for cooling air and the 4mm mounting screws; also in the shot is the spindle housing; it was a slide hammer for yrs; and did a good job; but now it's going to serve again; the dia is for the upper brg I still have to make the preload sleeve too; thats why the 3rd brg is not installed yet
Now we needto tackle the elelctrical safety side of the project
The mounting screws counter bored into the Alum angle; top is a none roller limit (Z upper)
