X2 Milling Machine
24/03/2024
This was my Brother's milling machine that is now in my possession. I didn't really know whether to keep it or sell it as I already have the Eagle mill and the little X1 Mini mill but there was room for it in the new shed so I will keep it, at least for the time being. It may be useful, especially as it has a square column.
I decided to make a couple of modifications to the mill before using it. One was to replace the standard tilting column with a fixed one available from Arceuro and the second mod was to convert the Morse taper 3 spindle to R8 so that I could use all the tooling from the Eagle mill. I don't like morse taper tooling as you often have to beat the crap out of the spindle bearings to remove the tooling whereas R8 just needs a light tap.
The fixed column comes as a complete kit which includes a new stronger column and a new base casting which gives more Y travel than the standard base. The kit comes with a longer Y axis leadscrew to allow for this so you get quite a lot for the money. The new column just bolts straight onto the base so should be a lot more rigid than the tilting version. To be honest, I have never found a situation where tilting the column would be of any help when machining something.
I think the column is really meant for the later SX2 mill but the X2 head and the X2 table fitted with no problems. The only problem that I did find was that the bottom mounting holes for the electronics box which mounts on the rear of the column were in the wrong place. The SX2 uses a longer electronics box so the bottom mounting holes are too low down for the X2 box. The mounting screws are also M4 whereas the X2 screws are M5. Also, the threaded holes for connecting the earth wires are in the wrong place for the X2 box. No real problem though. The top two mounting holes are almost in the right position so I just drilled and tapped these M5. The bottom mounting holes were them marked out and also drilled and tapped M5. Three new M5 holes were then drilled and tapped near the top for the earth connections.
However, changing the spindle from MT3 to R8 was not as simple as I had thought. Unfortunately, I didn't take any photos of the conversion as I wasn't going to write it up.
I wrongly assimed that it would be a simple case of swapping the spindles but it's not. The MT3 spindle is the same diameter (30mm) all the way along but the R8 spindle is a larger diameter (35mm) for the bottom half to account for the larger spindle bore needed for the R8 tooling. This means that the bottom spindle bearing is a larger bore than the MT3 bearing. That was not a problem as I was going to replece the bearings with some better quality ones anyway. The top and bottom bearings for the MT3 spindle are both type 6206. The top bearing for the R8 spindle is the same but the bottom bearing needs to be a 6007. These are all deep groove ball bearings. I would have liked to fit angular contact bearings instead but the bottom bearing would have been at least £70 and I didn't want to pay that much for a mill that might not get much use
The major problem is with the speed reduction gears. The originals are plastic which have caused no problems but I had decided to replace them with steel ones for a longer life.The plastic gears are a one piece molding with two gears and a spacer in the middle. To get them to fit would have meant boring the larger bottom gear and the spacer out to 35mm bore and the spacer is not thick enough to do that (I presume that the X2 fitted with the R8 spindle as standard must use a different gear set) It might be possible to remove the two gears from the centre spacer then make a new larger diameter spacer. The larger gear could have then been bored out to the required size. The top smaller gear does not need to be bored out as the part of the R8 spindle that this runs on is 30mm as on the MT3 spindle.
Unfortunately, Arceuro only seem to sell the gears for the MT3 spindle but The Little Machine Shop in the USA do advertise a complete kit to do this conversion which presumably has the proper R8 gears. It was out of stock when I looked though.
The steel replacement gears and the spacer are all separate items so that made the job much easier. The larger bottom gear was bored out to 35mm and also the spacer. The only snag is that the larger gear and the spacer both have a keyway cut in them which is mostly removed by the boring. I just recut the keyway in the larger gear in the mill and left the spacer as it was. Instead I shortened the key that fits in the spindle so that it only drove the larger gear. In the R8 spindle the smaller gear is driven by a separate key anyway (The MT3 spindle has one long key that goes through both gears and the spacer)
The only other modification was to make a new spacer that goes between the bottom bearing and the bottom large gear. The original is plastic and not very thick so would not have stood boring out. I just made a new one out of an old bronze bush from the scrap bin.
After all the modifications the spindle was reassembled into the head with the new bearings and the new gears. I also repleced the bearings for the contershaft at the same time. A big sigh of relief. It was then that I realised that I had fitted the spindle into the head upside down! Much bad language and I packed up for the day, having had enough. The next day I tackled the job again, removed the spindle and refitted it the right way up this time. The job went a lot faster the second time around!
After refitting all the electrics I tried running the mill to make sure that I had reconnected everything correctly. I was rather disappointed with the noise that the mill makes. I think it's the metal gears and they are incredibly noisy. This may improve as the gears run in a bit but I can see why people fit a belt drive conversion to the mill and get rid of the gears altogether.
Refitting the table and the x and y leadscrews was straightforward but I had to straighten out both of the gibs as they were bent. The surface finish on them was also pretty poor so they were cleaned up by rubbing on wet and dry paper on the surface plate. The gibs still need adjusting but that is a job for another time. I also need to replace the way covers as the originals had split and fallen to pieces.