Squaring up the Genmitsu 3018-pro after some upgrades. Normally this would be done with a DTI held in the chuck. Rotate it back and forth to understand the fore-aft tilt of the head. Rotate it left to right to understand the tilt of the head. In this way it is possible to very accurately adjust the head of the milling machine so it is perfectly square with the bed.
This was after my significant upgrades to the 3018 that turned it into a 3020-pro max, well, nearly.
However, the Genmitsu 3018-pro is a small desktop machine and the DTi is just too big. This is when I thought I needed to go back to an old method. First though I needed an arm that could rotate in the chuck so that I could measure it’s height above the table.
Here I’m applying this to a desktop cnc machine. However, this alignment technique works with any machine where you have a spindle and a table that you need to align to eg Pillar Drill or Milling Machine.
Dog Leg Pointer
You need a reasonable distance from the spindle axis to the measuring point. This distance and the height difference determines the angle. If the distance is too short then you will need to measure smaller differences in height.
The dog leg itself is not very big, just 1/8″ (3.175mm) diameter mild steel. I machined a point in the lathe before bashing two 90° bends. The dog leg is roughly 30mm long. Thus we are measuring over a distance of 60mm.
I was careful to leave a long enough shaft that would fully engage with the collet. This needs to be held firm.
Hold the dog leg in aluminium jaws in the vice to protect the shaft that goes into the collet.
With feeler gauges and some care it is possible to measure a height difference of 1 thou, 1 thousandth of an inch.
This is 0.0254mm over a hypotenuse length of 60mm. This is a minimum angle of 0.024°
Thinking of it more simply this means the machine will cut a slope on the workpiece of 0.0254mm in something 60mm across.
That should be good enough for this machine.
This is quite simple to use. You can use the pointer directly on the table with feeler gauges. However, as the table has T-slots I find it easier to use some blocks. I used gauge blocks as I know they are flat and parallel. However, a piece of plate material will also work fine.
The idea is to swing the arm front to back and measure the height above the block with feeler gauges.
You will need to adjust the spindle height so pointer is just clear of the block. Then slide a feeler gauge between the block and the pointer. Swing the arm around, move the block and repeat. Then adjust the head to correct any difference.
Once you have done front and back you can then do left and right. Again adjusting until the head is upright.
This is a very simple measurement that just takes some time and care to get right. The benefit is the cutter will not dig in on one edge and it will not create tram lines or ridges.
This video takes you through the process of getting the table flat and getting the head square.
For my first venture into CNC I thought I would buy a Sain Smart Genmitsu Router 3018-Pro. This is the low end of CNC engravers and at the time mid-2020 was around £200.
This is my homemade conversion of a Genmitsu 3018-pro to a 3020-max. Maybe not exactly a 3020-max, but a lot of the changes have been included. Plus I think the spindle upgrade I’ve made is better. The spindle upgrade was designed and made some time ago.