What type of end mill

[pgrbffParticipant @pgrbff]

[pgrbffParticipant @pgrbff]

I recently tried to post the following without much success. I'm not sure if it was removed but I meant no harm.

"I enjoy the challenge of making parts for my model helicoters and have had great help on this site with learning how to perform simple engineering tasks. My problem is that whilst I enjoy the practical side, I don't have my own machines and rely entirely on using a neighbours workshop. Add to this that I usually end up buying my own tooling and large pieces of stock, it works out extremely expensive. What is the best way to find a small workshop that is happy to perform small jobs? The drawing below is an example of the type of parts I need."

In my desperation I got in the car and went in to the local big town and found a small workshop, paid my money and duly put the parts produced in the bin as they looked like they had been carved out with a sharp spoon on an electric drill.

I therefore have to make them myself.

I have purchased some 12x12mm stock. What cutter will give me the best finish when milling out the centre hollow? I will be using a Bridgeport, but it is unclear to me the relationship between cutter diameter, number of flutes and finish achieved.

If anybody wants to do them for me I'm still game!

 

 

Edited By pgrbff on 05/03/2012 12:12:28

[JasonBModerator @jasonb]

You could hog that out quite happily with a 1/2" or 5/8" cutter 12mm or 16mm if you prefer metric. A 4 Flute cutter will be fine.

Best approach will be to take the depth out in 4 stages, 3 of just under 3mm and then a final pass at finished depth, same method wiyj the sides of the recess machine slightly shy of the edge and then take a final skim to finish only say 0.005" or 0.1mm.

Use a cutting fluid on alloy parafin or WD 40

J

[pgrbffParticipant @pgrbff]

Thank you. Is it OK to climb cut with end mills? Do you get a better finish if you mill with the rotation of the cutter or move the workpiece against the rotation of the cutter? I'm so used to wood and routers I'm not sure where to start when it comes to metal.

[JasonBModerator @jasonb]

As you have not used one much stick with conventional cutting. It is possible to climb the last few though full depth cuts but should not be needed. Unless you know the amount of backlash in the machine its safer not to climb cut as the tool can dig in if there is excess slop.

[EtheAv8rParticipant @etheav8r]

It is a pity you are in Ireland and not Cambridgeshire. I am putting together a new workshop with lathe and mill and cnc mill at that, and am a beginner with everything to learn. I am also into flying R/C helicopters and would like to make some usefull parts for that purpose one day. If you were local, then we could have got together.

[pgrbffParticipant @pgrbff]

My immediate neighbour has a mil and lathe, but I hate asking for his help, he isn't an enthusiast as such, just wealthy with a big house so he buys what he wants! Having said that he does help when I ask. None of his equipment has readouts, relying on traditional measuring techniques – it just takes me too long.

On the other hand I love the flying and am in the middle of converting a Sylphide 50 to electric. I'll get there in the end.

Thanks for the offer. What I need right now is a small shop that doesn't mind doing small jobs.

[M0BNDParticipant @m0bnd]

Try to find a local hobby group, if they can help then brilliant. Also try to work out what it would cost to get the parts you want manufactured, then work out what the cost would be to set a small set up for yourself? You may find that it would cost less to set yourself up for now and for future? Back to what you may need to make the above; a 1/2" or similar (12mm) 2 or 3 flutes would work better than 4 or more. Think about the end holes, would you put them in 1st?? It may be easier before removing all the middle material??? Try 1/2" x 3/8" stock 12.7 mm x 9.525 mm – it may be good enough???

hope you enjoy venturing into engineering, I have done it for the last 26 years and will continue for the rest of my life!!!!!

Andy.

[thomas oliver 2Participant @thomasoliver2]

Even small engineering firms are not really interested in a run of two. These items would be milled as one piece then slit into two. Milling cutters are not designed to plunge cut or take heavy downward cuts. Slotting drills are so designed and have unequal cutting edges, the longer one sweeping the centre area. They can cut down like a drill or sideways. Used on a decent alloy like HE30, they will produce a good finish if the cutting rate is kept high. Any reasonable size slotting drill say from 8mm up would do as there is ample clearance. Avoid climb milling. Tomol.

[JasonBModerator @jasonb]

Have a read of this post by Bogs, it gives a good description of removing the majority of the metal and then skimming the final few thou.

As you don't need to plunge cut and the recess is wider than a singel pass a 4 flute cutter will give a finer finish.

J

[pgrbffParticipant @pgrbff]

Thanks. I remember looking at that before. I'll have another read through.

[Axel BentellParticipant @axelbentell]

For making chopper parts, even for 90 sized ones, u'd hardly need a very big machine. I'd say a Taig or something like it should be perfect. Get all good books on machining u can, they save u money in the long run! I like Sparey very much, and the Home Workshop series are superb too.

If I were u I'd get a sherline with mill column, and a hand shaper as a compliment too it.

[VersabossParticipant @versaboss]

Posted by JasonB on 09/03/2012 07:38:13:

Have a read of this post by Bogs, it gives a good description of removing the majority of the metal and then skimming the final few thou.

So even to a capacity like Mr. Bogs is not free of doing stupid mistakes – and nobody seems to notice it. Ok I did not read all comments…

In the first 2 pictures he numbered the 4 sides of the bar (going clockwise) 1-2-4-3.

But in the next pic it suddenly is 1-3-4-2.

Quite confusing for a newbie, methinks… when the description tells which side has to be at which position.

Greetings, Hansrudolf

(a bit sorry about hijacking – but that's not the worst thing happening here)

[AndyPParticipant @andyp13730]

Or it could just be the other end of the block !

[JasonBModerator @jasonb]

As Andy says its the other end of the bar, read what Bogs says

"Mark each end of the rough cut bar as shown"

J

[Ian S CParticipant @iansc]

If all else fails, a file and hacksaw, and a bit of time (not too much), and you can have near as accurate as a machined piece, and proberbly quicker than getting your self to some one with a mill, setting up, the job on the mill then is just a few miniutes, it takes longer to clean up afterwards. Ian S C

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