The Evolution of a Home CNC Mill

[Stevie]

Some of you regulars will remember this conversion of the $58 Delta drill press into a 4 axis mill




Well it is now undergoing a complete re-build with most of the original Delta parts removed or so drastically altered they are really new parts; I'll add some of the old photos as needed; most seem to have gone from my HHD; but some are still here
Here is the new base plate with risers and THK rails; please keep in mind I use whats on hand; and it had better be cheap; but good and fully useable

Here now added is the Vertical support for the Z axis; this part is hardened stainless steel; and was scrap; I saved it to live again

The small compumotor stepper for the Y axis is not going to be used; my good friend Catch22; who also will be posting his build of a new cnc lathe donated a 2 stacker (way to go "bud" )
Those are SR25V for the X axis
The ballscrew was on the X before; the Y is a new Universal .200 pitch 2 start ground leadscrew 0.0008/ft accuracy
The Vertical will be handled by the Kerk .400 lead 4 start leadscrew; the load will be balanced
Motor for the spindle is a RC aircraft starter re-built with new endbells and ball bearings; running at 30.8VDC it seems it draws 2amps no load (RPM still to be measured)
The said motor below

All who followed the new spindle for the old version of the mill will remember this photo

I have now made the quill active once again; so I'll have 6.187 active travel on the Kerk and the THK rails; and the live quill will be able to drill/tap etc in manual mode; or locked for the Kerk/rails to mill

Here is the modified head; as you can see; massive changes
I cut off the normal round mount; then milled it flat; I then milled inside both sides to form a Key to maintain accuracy and stop movement; there are 2 webs inside to form the quill guides; I used these to drill and tap into to hold the Alum block; plus 4 5mm caps in the sides also into the block
The top is milled ready for the motor mounting plate; which will also tie the head to the backplate
The 2 locking screws can be seen to keep the quill tight; the recoil spring is once again in palce


Bit more done; the Y screw mounting blocks are in place; the nut carrier is next here to make; table is now in place and moves nicely; I tried 3000mm/min rapid; worked great

Here is the complete Y axis screw with both supports and the nut carrier; the nut carrier is split to enable clamping to the nut

The rear support screwed down 5mm caps

The belt reduction; plus the alum angle will form the belt guard and help cool the stepper; it is now alive on 2 axis

The drive motor mounted; speed 9860rpm; or whipping around really fast LOL
The Z axis screw is 1/2 mounted; the head is being supported by it now; 16lb of counter weight as of this part of the build; add 2 pulleys; the SS slide covers and belt with guard; I figure about a 20lb should do nicely

Ok big day
The 2x2x1/1/4 angle makes up the 2 supports; these are then screwed to the vertical main support; the 3x3x1/4 angle is screwed to them with 6 8-32 and 2 6-32 countersunk SS screws; it also forms the basis/support for the stainless steel sliding cover I'll be adding to keep chips/etc out of the ways; and holds the housing for the upper bearing of the KerK screw; the stepper mount will be screwed to this also
I milled the angles to maintain true 90's and remove the excessive web raduis
I'll have to bush the timing belt wheel tomorrow for the Kert
4 5/16" capheads hold the whole thing to the back support

Z is active now; the Eastern Air Devices seems happy with no counter weight but I'll add one anyways; to remove the load from the Kerk


Here are the pulleys at speed; my camera has actually stop/actioned the motor pulley and you can see the 4mm setscrew hole; wow (5375rpm)
The fan at the bottom of the pulley is from a CPU cooling fan/heatsink
Speeds are close to what was predicted by my calculations +/-250rpm
Top speed 30.5 VDC = 16000 at 12VDC = 8000
2nd speed 30.5 VDC = 10250 at 12VDC = 5100
3rd speed 30.5 VDC = 5375 at 12VDC = 2650
4th speed 30.s VDC = 3950 at 12VDC = 1500
5th speed 30.5 VDC = 2190 at 12VDC = 1090


Here is the anular airpassage; this will have some open cell foam insterted for cutting; it will stop chips/dust etc
Basically a cap over the end bell


Found a small problem with running 16000; thetop bearings on the stub shaft got to 40dgr; this second fan will help with stopping that


Here is the 30.5 VDC power supply and the switch for the spindle


Here is a close up of the counter weight and the ass pulleys to lower the friction of the set-up; the 2 brass pulleys ride on 5mm bore ball races


The Y axis pulley is now safe from little fingers


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 table extension; the other side will be rubber or SS not sure yet


The mounting screws counter bored into the Alum angle; top is a none roller limit (Z upper)
The bottom 2 screws hold the Z axis home switch

Said home switch

Here are the X axis home (bottom of the shot) and the X axis limit; I have the software limits active too

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


The X axis Stainless Steel way cover


Same just retracted; the middle section rides the SR25 rails on 2 UHMW blocks; rubber pullers maintain the correct distances as the covers pullout


But will it work---------------- Yes
Here is the cut to ensure the table is flat to the ways in X and Y; 0.2mm deep at 350mm/min
I'll be adding a coolant groove around this flat area; and I'll mill the remaining table 0.1mm lower than the top; then I can overhang the main work area; and be able to drain any collected coolant

BTW; I should add; the orange you see behind the table is a new Y axis cover made of Silicon rubber 1/32nd thick; the black rubber is 1/16th thick; the black stuff was too much back there; it bunched up and even tripped the lower Z limit once
It may get replaced with Stainless steel if I can get the hang of bending it just right


Table is now just about finished; still need to add 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

Next I still need the Lower Z SS cover; finish the top SS Z cover; I have 1 week off work so I think I can finish this machine pronto

More to come; I'll edit this to add more info and photos as the build progress

[pminmo]

Wow, nice work!

[CJL5585]

I second the motion. Great Job.

Jerry

[Stevie]

I just ran the re-built motor with the bearings in place; I have not cut any cooling holes yet; but she sure sings; very quiet and tons of power; The case and end caps did get a little hot (nothing like a stepper though)
I will be adding a fan and cooling holes in each end cap
Running with no load she's pulling 2.08amp @ 30.8VDC
I managed to hold the shaft and get the amps up to 5; but it did burn my fingers in a hurry; I would not do that again; LOL

[margni74]

Ill be watching this with interest, looks damn cool.

[Stevie]

Thanks for the replies guys
I just want to add; to make these machines I'm using machines that are just about the same age as me; some are even older (if thats possible) LOL
The Bridgeport is circa 1957; I went through it and I am now re-building another one; looks like we'll sell the 2 and buy one new one; yeppee

[praetor]

...What about the details on how was it done for those salivating for a project like modifying this type of benchtop drill press? Where and how to get the materials rated for speeds and feeds for the new spindle for this drill? What to place where in the new spindle? All I want to know is the modified headstock assembly info/details. the CNC mechanics and electronics I can do myself. I am sorry If I come off sounding as I do. But no one would pass up the oppurtunity to modify this drill press given the chance. I mean just look at the pics here. It's inspirational, it's ingenius! All this time, owning two benchtop drill presses like this one above, and I never thought of making them into a mill let alone a CNC mill like the one pictured above. I don't have the design skills it takes to come up with this idea, basically I don't have an imagination, I just follow instruction. It is a thing of beauty, Stevie. so what of it? Care to share the details? It's as they say, simulation is the best form of flattery.

[Stevie]

Preator; I have read your post 3 times now; I'm not too sure just what your asking me

[hllrsr]

He's asking if you would please be nice and share the information on how you originally converted the drill press to a CNC mill.

BTW, Damn, that is a nice job you've done on the conversion!

[CATCH22]

The Man Knows His Stuff,nice Work Steve.

[Stevie]

Originally Posted by hllrsr He's asking if you would please be nice and share the information on how you originally converted the drill press to a CNC mill. BTW, Damn, that is a nice job you've done on the conversion!

Ok I see; well I did post most of the photos have gone from my HDD; and the FTP i used to use has been deleted; so there is no way to get those photos back; as they say a picture is worth a thousand words; i'd sit here forever trying to discribe what I did; and most likely it would not be that clear; really the drill conversion was only successfull for brass/alum and plastic; thats why I'm converting it; the spindle change was to stop the chuck falling off; and to improve accuracy; plus gain a big increase in speeds; 3100rpm is just not enough for a 0.010" ball cutter

Thanks Catch22; we did have fun watching the rapids tonight and the program run; even if it was just 2 axis moving

[Jason Marsha]

Great Work. Keep the pics coming.


Jason