Mystery Milling Issue?

[andy_con]

so i have a bit of aluminium i want to turn into a diode holder.

my mill is fitted with dro's on all axis, so i measure the required distances onto the bit of aluminum.

the first thing i need to do is make a 4.5mm hole right through, ive tried straight drilling with a drill bit, ive tried using a spot drill first then a drill bit and ive tried using a slot drill (flat milling bit)

next is make a 5.7mm cut for the actual diode, this is done using a slot drill (milling bit). i paid £20-25 for this bit so its very good quality.

i then flip the bit of aluminium and remeasure into it so i can enlarge the first 4.5mm hole i made right throught. ive checked using a center finder to make sure its exactly aligned.

i then use an 8.5mm slot dill (milling flute) to drill a hole

last i tap the hole.

i then screw in a len and its off centre, so off centre you can clearly see with your eyes its off.

how, why...........

this is causing me massive issues and i just cant seem to solve it. i have all the tooling needed to get it perfect, ive double checked the vice and the milling head are aligned using a dial and again perfect.

ahhhhhhhhhhhhhhhhhhhh just fucking ahhhhhhhhhhhhhhhhhhhhhh

[LaNeK779]

well, is there a chance that your initial 4.5mm through hole is not straight?

[andy_con]

umm not sure, as ive said ive tried straight drilling with a drill bit, ive tried using a spot drill first then a drill bit and ive tried using a slot drill (flat milling bit)

[p1t8ull]

Is this with a 2mm FL lens, and do you have any adjustment in either the diode or lens position in your mount? If so then as I said in my mail, I think that's your problem.

On Dave's adjustable mount you get about .45mm total adjustment, and can move the beam around a hellava lot with that small amount and a 2mm FL collimator.
Sounds like you are doing everything right, but you could have .1mm offset in the diode position, same again or maybe more on the lens position, and then there's the thread..

[andy_con]

its not that simon, when you screw the lens all the way in and remove the diode. you can clearly see the lens isnt centred, its off centre and this is why the beam is coming out at a big angle.

the 5.7mm diode hole allows for fine adjustment of the beam, but this isnt fine adjustment

as far as i can tell you can adjust the head on the mill so its always parallel to the table

http://www.toolshopdirect.co.uk/pdfs/sealey/SM25.V2.pdf

[chad]

Hi andy some pics might help.

First you always have to make a spot hole for drilling holes if you are planning on going more than 2 the diameter. Drill bits wander.
You want to be using stubby, or screw machine bits : http://www1.mscdirect.com/eCommerce/...Bits/_/N-77h72

They are shorter and more robust for drilling deep.

Are the holes always off in the same dimension? Make sure there are no burrs when you flip it. Never use an end mill (slot drill) in a drill chuck. Drill chucks are goof for fast holes but they have much more runout than a collet or end mill holder. I would recommend using collets for the drills and spot as well if you really want a clean hole. End mills in a collet are going to give you a much straighter hole. Drill bits are not a precise tool. They just make holes fast.

Whatever corner you use for your x0,y0,z0 use that same corner when you flip it. If you are using a center finder on a crooked hole all you will do is find the center of the crooked hole. Double check your dro slides make sure there is not something sticky messing up a reading.

chad

[tonyaztec]

Can the angle of the bed be adjusted, maybe it not at 90 degrees to the head, when you flip the aluminium everything would be a mile out.

[andy_con]

Can the angle of the bed be adjusted, maybe it not at 90 degrees to the head, when you flip the aluminium everything would be a mile out.

got a dial and everything is aligned perfectly

[andy_con]

no pics to hand as i want getting thr hump after 17 attempts

also ill add i use an electronic edge finder to find the edge of my work

Hi andy some pics might help.

First you always have to make a spot hole for drilling holes if you are planning on going more than 2 the diameter. Drill bits wander.
You want to be using stubby, or screw machine bits : http://www1.mscdirect.com/eCommerce/...Bits/_/N-77h72

They are shorter and more robust for drilling deep.

Are the holes always off in the same dimension? Make sure there are no burrs when you flip it. Never use an end mill (slot drill) in a drill chuck. Drill chucks are goof for fast holes but they have much more runout than a collet or end mill holder. I would recommend using collets for the drills and spot as well if you really want a clean hole. End mills in a collet are going to give you a much straighter hole. Drill bits are not a precise tool. They just make holes fast.

Whatever corner you use for your x0,y0,z0 use that same corner when you flip it. If you are using a center finder on a crooked hole all you will do is find the center of the crooked hole. Double check your dro slides make sure there is not something sticky messing up a reading.

chad

[chad]

Another thought.

Make your 8.5mm holes first, then tap, then spot, then drill through. Then flip and do your 5.7 counter bore. Use a vice stop in the x axis.

Also lock your ways when you are working on a hole.

also be sure to start the tap in the machine ( just snug in the drill chuck) turn by hand to get it started. If your tapping is off that will mess up your alignment as well.
chad