I also used Alum see this post #11 http://www.mycncuk.com/threads/8903-...highlight=alum I am not sure if there are different strengths of Alum
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I also used Alum see this post #11 http://www.mycncuk.com/threads/8903-...highlight=alum I am not sure if there are different strengths of Alum
Nifty solution, thank you.Quote:
Originally Posted by mekanik
I used a 3 flute straight M5 tap with some cutting oil. Did about 50 holes with no problems at all (once I’d drilled everything to 4.2). What would be the advantage of solid spiral tap?
The best taps I've found for through holes in ali are the blue ring spiral point types like this:
Attachment 25793
They're made specially for aluninium, the interrupted thread higher up seems to help with binding. Typically I've found you can tap a hole in 12mm plate in 3...4 seconds with one of these in a cordless drill with some cutting fluid. For blind holes as Mekanik said you need to use a spiral flute tap (to get the chips out), again I've found the blue ring types are marginally the best.
This might be of interest
http://www.europatool.co.uk/threading/application-taps
Regards
Mike
In a nut shell for taps-
Spiral Point - Only good for through holes, as they push the swarf forward through the hole.
Spiral Flute - good for blind holes, as the swarf comes up around the shank, but are more prone to binding if the swarf doesn't clear.
My preference is always spiral point, as they're the stronger option.
If you're only going through relatively thin section, I'd avoid the interrupted flute ones Voicecoil posted a pic off, as a bit inadvertent sideways pressure with only two or three support flutes engaged can quickly jam the tap and snap the tap/rip the threads out the hole.
As always, lubrication is key. For tapping aluminium, a drop of good quality cutting oil is essential to stop things sticking.
There are also threadforming / roll forming taps which can give a stronger thread in aluminium, but drill hole size is very critical, so I would advise against them unless you can control the hole size well. Undersize and the tap will quickly jam, oversize and you won't have much of a thread.
Here's an alternative manufacturer's product being demonstrated...Quote:
Originally Posted by bluesking
https://www.youtube.com/watch?v=9zBl9yLacWs
Hi Bluesking
Just seen your post here. Well done for joining the forum, doing a design and taking advice!. I wish I had seen this earlier because I would have told you to get the parts water-jet cut which also would have done some of the bigger holes for you and spotted the rest. This is the approach I took on my build and saved me a lot of grief (see build here http://www.mycncuk.com/threads/8206-...Axis-CNC-Build post #10 ) All I had to do was counterbore and thread the extrusions using a spiral tap. I then used a finishing tap to clean the threads or a plug tap where the hole is stopped.
Regards
Michael
Hi guys,
Have not been on for a while as have been busy sorting out my new workspace and stocking up on parts. Thanks for everyone's various messages - don't have time at the mo to answer everyone individually.
Its all go on the CNC front now my space is sorted and I have all my parts, so I wanted to post an update.
Today I built a table for the CNC. 18mm MDF & C16 CLS timber from B&Q. About £30 worth of materials:
1 Cutting to size
Attachment 25845
2 Table top is 900mm x 1220mm; Supported by a timber frame:
Attachment 25846
3 700mm legs screwed on to table top:
Attachment 25847
4 timber base frame for support and shelf:
Attachment 25849
5 MDF shelf for base frame, and a few corner supports for increased rigidity (may need more of these in the short-dimension in future)
Table finished, ready to start assembling the machine itself:
Attachment 25850
Looking good. Just a thought - is MDF the best, most appropriate worktop for something that could end up working with water (if only a failure-case for the spindle coolant, for example). My point - I have a sacrificial MDF layer on my "electronics" bench - and that's suffered some small water damage from an ultrasonic bath - and the surface is now perpetually feathering and impossible to flatten. My personal preference atm is ply, but most of the shops are stocking cheap eastern boards with large filled voids. The bench I've used for the mill is steel framed with ply top, sheathed in 1.2mm steel sheet (I had a bit lying around) - that's tough as boots.
I'm assuming that the bench is entirely separate from the machine? (it doesn't form part of the machine build?)
Yes it is a separate bench - not connected to the machine - though I will probably mount the X cable chain directly to it. I will mount the electronics to the lower shelf for now and see if this causes any problems.Quote:
Originally Posted by Doddy
I'm using an aircooled spindle so hopefully no issues with moisture.