Thanks Bernd
After having milled a bit, i believe some of the irregularities come from that the tram is not perfect, and I milled each step with about 90% of the cutter width, making the ridge extra high. When I now progress about 50% of the cutter width for each pass, I get a much smoother finish.
To answer the two other questions I had:
- 0,20mm (and other thicknesses) and 400mm long shim stock can be had at tool stores. They actually sell feeler gauges on a 3m roll for next to nothing. When I'm done with the current milling project, I'm going to measure the gap at the gib and buy a suiting roll.
- To make the mill table flat and shiny, would require fly cutting I believe. But this is not to be done before I have shimmed all gibs to a nice snug fit, and if the ways are overly worn, I'm going to have to consider disassembling the table and having them scraped. I know nothing about scraping, so any advice is well appreciated.
Now over to my new project for the mill. It is actually a project for the lathe, but it requires a lot of usage of the mill, and I have learnt a bit about milling by making it, so I thought I'd post it here.
As of now, I do not have a parting blade that I can use on my lathe. The big one in front on the picture is so large that if I were to mill down the holder to get it to the centre height, the mounting shoulder would only be 5mm thick afterwards, and the small one is for 25mm high blades, while I only have a 20mm blade. So I went searching for a lump of steel, and drew a c-o-c
As I don't have other ways of cutting steel than the angle grinder, I figured I'd try to do like AdeV and part it on the mill. I used some water cut plates of stainless as paralells, scribed a parting line and put my only 8mm carbide roughing endmill in the collet chuck.
Locking the X-axis ways, I took 2mm passes at about 800rpm and 100mm/min if I remember correctly.
Until I eventually ran out of space
I then moved the end mill out long enough to be able to cut through the part. I then slowed down the feed a bit and progressed with 1mm passes, until I was about to cut through. As I have very few endmills, I thought I'd try to be as carefull as possible when parting of, so I made a through cut from each side towards the middle, but left a few mm of steel standing out. Then I just wiggled the loose piece until It came of
Afterwards I progressed to my 16mm end mill and shaved of 0,5mm in hope for a nice finish. Well the result was OK, nothing more.
Not changing the setup in the vise, I progressed and milled the top flat aswell.
I then flipped the part over and milled down the third side, which has a starting hole from the water jet, so I had to mill it down 3-4mm. I believe I used 540rpm, 110mm/min feed and 1,5mm depth of cut on a 16mm HSS endmill.
When that surface was fine, I also milled down the last surface, and placed it in the vise for cutting in the X-direction
The part was 37mm wide, I needed a 20mm slot, but settled for 19mm before finishing cuts. Subtracting 19 from 37, and dividing by 2, I reckoned I should have a 9mm edge on both sides of the slot. I started the mill, moved it close to the surface, put a piece of paper between and cranked the Y-axis handle until it just grabbed the paper. I then moved the Z-axis down, to avoid starting a cut, and progressed the Y-axis handle 0,10mm further. I then assumed I was at the edge of the piece.
Next step was moving in the 9mm, plus the cutter diameter. I didn't use my head, so I figured since i used a 16mm collet, the end mill would also have to be 16mm, so I cranked the Y-axis handle 25mm and made the first cut. To avoid backlash between cuts, I made the first cut 3mm deep, then moved the Y-axis (in the same direction as I started, to take out the full turn of backlash
) handle 3mm and took the remaining cut. But when I tried fitting the parting blade, I expected it not to fit as the slot shoudl be 19mm, but instead, it slid in and still hade some room to wiggle.
After going through my calculations for the fourth time, I figured the only thing that could be wrong would have to be the endmill, and yes it was. Though the shank is 16mm, the cutting diameter is closer to 18mm
Before I started this project, I had drawn up many different concepts of how to make it. I initially settled for trying to make it similar to the Sandvik holder I already had, only 5mm shorter, but this mistake eliminated that option. My other option then became to mill an angled surface above the parting blade and fit a plate to hold down the parting blade.
So out came my fancy angle measurement kit
After the first pass, I decided 45 degrees was too steep, so I reduced it to something that looked more sensible. I have no clue what the angle is
After finishing the angled surface, I decided to drill mounting holes for the screws to hold down the plate. I thought I'd do it the proper way, and marked up the centre line, put in the centre drill and started on drilling a hole. About 5 seconds in, this happened
I tried to get the broken piece out, but there was no way it was coming loose, so I had to drill the centre hole off centre. That's going to annoy me a bit..
Anyways, here are the holes drilled to 7mm, in the lack of a 6,8mm drill, as they are going to be tapped M8.
This is progress as off today. Next time, I'm tapping the holes and hopefully making the fixing plate.
Should I make the fixing plate of steel or aluminium? I was thinking about using aluminium to avoid damaging the edge of the blade, or is the tensile strenght of the HSS so much larger than for steel, that it's not going to be a problem?
