Milling with the Hobbymat

[internal_fire]

I have read in a couple of places that it is better to use a cutter wider than the job in this situation and also that it should be offset. This may be more relevant in ‘industrial’ use.

That is probably true for large industrial machines.

For lightweight, somewhat flexible machines it can be better to use smaller cutter sizes to keep the vibration under control. There may be "joint lines" resulting from the overlapping edges of multiple passes, but the end result will be smoother if the vibration is minimized.

And of course sharp cutters almost always work better.

Gene

[vtsteam]

When squaring up a piece of about this size, I found this method helpful:

<a href="https://www.youtube.com/watch?v=ZghLslZZ6sg" target="_blank">http://www.youtube.com/watch?v=ZghLslZZ6sg</a>

[Jasonb]

Here are a couple of cuts on a piece of EN8

cheap 6mm 4-flute carbide endmill that has only had a little use and is still sharp, nice long slivers of swarf.

First cut was a stepover of 0.33mm, the second 0.5mm. Height 0 to 10mm at the ccrestof the bar.

Also did a cut with a worn 12mm 4-flute HSS cutter but video of the cut did not come out, just the swarf at the end which is getting a bit crumbly although the finish is still reasonable.

<a href="https://www.youtube.com/watch?v=jpg4S3Wvqg4" target="_blank">http://www.youtube.com/watch?v=jpg4S3Wvqg4</a>

Usually some sort of offers on the carbide cutters so average £1.50 each for 4mm and 6mm

https://www.aliexpress.com/item/33041577316.html?spm=a2g0o.order_list.order_list_main.17.720e1802kN2Nb6

I would suggest trying a sharp new cutter first as it is the easist thing to change. If you still have problems, look at things like bearing preload. BUT do that with a warmed up machine as it could just be the cold had altered the preload a bit.

[Chipswitheverything]

Good tips throughout this thread, and the video of squaring up the aly block was entertainingly done and worked well for the light cuts taken on some very crisply machining alloy. I think that I might have liked a bit more initial gripping surface if needing to take a fair amount off a steel block.
Seeing the photo of Roger's milling set up using the versatile lathe / mill combination, with the lathe carriage effectively being the milling table, and with a neat but quite small vice attached, I would suggest that , even with optimisation of the cutter type, sharpness, and lubrication , the lack of metal mass in the arrangement is going to always tend to vibration snags when tackling tougher material like the EN8. The beefy machine tables and chunky vices attached , even of the hobby sized milling machines, do in themselves inhibit some of this difficulty by their inertia.  Dave

[john mills]

the video  uses climb milling  alright on machines with preloaded ball screws and using sharp cutters but on light ordinary machines the tool is
likely to grab the work  even running back without applying a cut even on larger heavier machines  espeshally if the cutter has done a bit of work and lost its edge  and the material is a bit tough
   john

[Roger B]

Thank you all once again for your inputs  I will pension off that cutter. I have tended to use it for squaring up pieces of steel as it is too big for most of my normal work.