I always recommend using the machine to cut metal before jumping to conclusions based on feel and a few measurements. The problem with accurate measurements is they're very easy to get wrong and then it's even easier to misinterpret what they mean. Approach with caution.

I find it better to cut known machinable metal with a sharp cutter at about the right rpm, depth of cut, and feed-rate. If the cut is the correct dimension and of reasonable finish, without horrible noises or smoke then the machine is 'good enough'. Note the need to test with suitable metal, not random scrap, and for the operator to drive the machine sensibly with a sharp cutter. The operator getting these wrong can produce worse results than a mildly worn bearing! So develop a reasonable level of experience before deciding what to do next.

Run-out of 0.001" suggests the bearings are on the way out but get to know the machine better before rushing to fix it.

Dave

.001" isn't the best but you will be able to cut metal, I worked on large mills for many years and their spindle run out was far worse than yours.

Tony

Well the less the better but we are talking about a hobby mill, an industrial machine costing £££'S should have little discernible internal spindle taper run out when new.

Tony

Well done! One small note: it is best not to run a dial indicator on a shaft revolving under power at anything above a couple of rpm. It puts too much strain on the dial indicator, and the dial indicator does not give an accurate reading at any kind of speed. It is a slow-reacting series of very high-ratio gears that don't do well under stress. Best to test your spindle by rotating it by hand, with no belt tension on the pulleys at all.

Good stuff. Have fun. The contemporary treatise on the subject would be Milling for Beginners by our own Jason Bellamy.

Hi I have the test report from the factory for my rdm350 with the specs that the mill should be when new the run out should be a max 0.02 at the top of the test bar and a max of 0.03 at a point 100mm below the first point.

Hope this helps

I've got RDM 350, had for 30 odd years and have carried out many mods to it, some following George Turners articles in ME 1989. I made a power cross feed, using gears from photo copier and a car window up down motor, not all wiper motors are reverse able.5 or 6 years ago I fitted a pre owned 3 phase motor and inverter, what a difference that made. I'm sure there are better bench top mills around, but I very happy with mine. I've found the best source of information about machinery is the US Grizzly site, all though 'tony lathes' has some, and he say Naerok is the best of the bunch. I have a manual, but the picture on the front calls it a REXON, and models which were available are RDM 400-500/500MF,,nothing about a 350 I think that was for the US market, but no test report. John

Happy Christmas to all

Hi Yes it did come with a manual and test report however the manual was for the rdm 400m/500m/500mf

the manual has been edited in pen where there are differences I think the manual was the same for all as far as I can tell I think the main difference between the 350 and 400 was the table being slightly wider. I can't seem to upload an image of the test report which i have found useful in the past

Edited By Kim Garnett on 26/12/2022 11:08:40

Edited By Kim Garnett on 26/12/2022 11:10:28

I also have an RDM350. It's a nice compact machine. Interesting to see the spec sheet Kim. I'll use it to assess mine

Hello Kim and other RDM owners, I've had a look at that address and its almost the same as my so called manual. The machine is so basic that its pretty obvious which each part does. If any one has the bearing manufactures part numbers for the bearings I would like to know of them. John.