Steve,
Its like turning plastics (delrin, etc) feed the tool too fast and the material heats from friction and melts or burns as the heat can't be conducted away as it can with metals. In turning, a large rake angle is best to produce continuous chips. With HSS, 200-500 ft/min. Carbide (I don't use it) its recommended that you turn at 500-800 ft/min.
Drilling is tricky as the cuttings tend to fuse to the drill rather than climb up and out of the hole so drill a bit, retract the drill, clean it then re-insert and continue drilling. HSS drills with low helix angles, point angles of 7-120 degrees. Feed rate of 0.001-0.012 in/rev for holes of 1/16" to 2" dia. Speeds of 100-250 ft/min. lower for very deep holes
I use my air gun to clean the hole and cool the drill bit.
I don't use a lubricant (makes a mess) but aqueous types are supposedly ok.
Most important is to keep the tool cool. Take it slow.
When drilling, as you approach the far side (through holes) the material tends to fracture out a bit unless you take it VERY slow.
If I'm drilling a large diameter hole I start with a smaller dia drill then larger then larger again, thus not having the drill hog out all the material in one pass. Of course, start a pilot hole with a center point drill as the surface is very slippery and the drill will wander.
Practice on scrap and you'll get the feel of it.
To cut sheets, table saw with a carbide blade.
Attached is a picture of a box I made with the stuff. I drilled and tapped #8-32 holes for flat head hex screws as you can see. Cut edges will be smooth but not shiny as the shine comes from the press mold the Bakelite is made in.
My old fluorometer pictures are pre-digital era but if you're interested I can scan them for you.
See http://www.oba-ic.com.au/pdf/020611_FabBakelite_0810v4.pdf
And http://www.bakelitehylam.com/indlamni.html
Also http://www.sumibe.co.jp/english/product/circuitry-electric/circuitry/sumilite-pl/spec/009.html
Bob
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
Sent: Saturday, June 23, 2012 12:48 PM
To: [log in to unmask]
Subject: Re: [TN] DH 99 Bakelite laminate - NTC
Bob,
Thanks! Interesting history. This plus Brian's!
I learned something new in this whole discussion - I did not realize that
Bakelite was machinable . I just thought it would smoke and burn if you
hit it with a mill. Is the feed & speed published somewhere?
I have an old Dumont scope that spent 20 years in the basement in Southern Indiana where the humidity gets nasty. All the knobs have white fuzz on them. Something apparently likes to munch on whatever plastic they are made from. Scope still works [but not as well as the much newer Tek!]
Best regards
Steve C
From: Bob Landman [mailto:[log in to unmask]]
Sent: Saturday, June 23, 2012 10:57 AM
To: TechNet E-Mail Forum; Steven Creswick
Subject: Re: [TN] DH 99 Bakelite laminate - NTC
Hi Steve,
I don't believe so. I have a large sheet of it (1/2" thick) in my machine shop in my cellar (old Victorian farm house with granite boulder foundation which does get humid and moldy on the walls). The bakelite is still as pristine as when I purchased it back in CA in the 1980s from McMaster-Carr.
I used the stuff to make what we called a T-format spectrofluorometer - the Bakelite surrounded the sample compartment and the two photomultiplier tubes as it made an excellent opaque thermal insulating compartment. The quartz cuvette was placed in a square block of OFHC copper bonded to and heated/cooled by a thermoelectric plate via a feedback loop from a thermocouple that measured the water temp.
My customers (scientists) were measuring the intrinsic viscosity of neuronal cell membranes using a very cleverly designed fluorescent probe molecule that was absorbed into the membranes. Polarized UV light illuminated the solution and if the fluorescent probe molecules tumbled quickly, the emitted visible light was depolarized. The signals from two PMs with polarizers oriented 90 degrees to each other were then processed to yiled a log ratio which was the measure of the fluidity of the membranes. Couldn't have done it without Bakelite.
I found in an old text "Handbook of Engineering Fundamentals" edited by Ovid Eshbach (2nd ed. 1952) the following electrical properties (chp 13- p73)
Bakelite, wood molding mixture 17.7 to 21.6 Kv per mm, 1X10(12) volume
ohm-cm, 4.5 to 5.5 air unity (?) specific inductive capacity
Bakelite, asbestos molding mixture up to 9.8 Kv per mm, 4X10(11) volume
ohm-cm,
Bakelite, Micarta-213 (I think this is what I have) up to 31.4 Kv per mm,
5X10(11) volume ohm-cm, 5 air unity (whatever that is!)
(volts per mil, multiply Kv per mm by 25.4)
References from General Bakelite Co which Baekeland founded in 1910
Ah, the good old days....
Bob
_____
From: Steven Creswick [mailto:[log in to unmask]]
To: [log in to unmask]
Sent: Sat, 23 Jun 2012 07:28:43 -0500
Subject: Re: [TN] DH 99 Bakelite laminate - NTC
Bob,
Is Bakelite a nutrient to fungus growth? I seem to recall seeing fuzzy white stuff growing on old O-scope knobs stored in a damp basement for a number of years. Possibly the knobs were not Bakelight..
Steve C
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Landman
Sent: Friday, June 22, 2012 12:29 PM
To: [log in to unmask]
Subject: Re: [TN] DH 99 Bakelite laminate
McMaster-Carr carries what to me is the equivalent (I have purchased large sheets of the stuff).
See http://www.mcmaster.com/#garolite/=i38d13
They call it Garolite
Bakelite is named for Leo Baekeland who invented the stuff. Us physics types used a ton of it over the years as it machines easily, does not dull cutting tools. http://en.wikipedia.org/wiki/Leo_Baekeland
Here are collections of items made from the stuff http://www.amsterdambakelitecollection.com/
http://kaufmann-mercantile.com/bakelite/
A book on its properties
http://pubs.acs.org/doi/abs/10.1021/ie50308a012
A lot more on it from ACS
http://portal.acs.org/portal/acs/corg/content?_nfpb=true
<http://portal.acs.org/portal/acs/corg/content?_nfpb=true&_pageLabel=PP_ARTI
C> &_pageLabel=PP_ARTIC
LEMAIN&node_id=924&content_id=WPCP_007586&use_sec=true&sec_url_var=region1&_
_uuid=82c1c58c-ec86-4aab-afc2-2949d2bc9b01
Bob Landman
H&L instruments, LLC
_____
From: Mike Fenner [mailto:[log in to unmask]]
To: [log in to unmask]
Sent: Fri, 22 Jun 2012 06:41:04 -0500
Subject: Re: [TN] DH 99 Bakelite laminate
Bakelite is/was a brand name for one of the earliest synthetic polymers, it's a phenolic resin.
It's likely that what is meant by 'Bakelite laminate' is paper phenolic, Bakelite being a brand name that tended to be used as a generic term.
(like
Gas , Xerox, Hoover etc)
Early PCBS were made from layers of paper impregnated with phenolic resin, and was replaced by glass epoxy years ago. It lingered in mass market stuff into at least the late 1970s as it was cheap. FR2 would likely be a functional equivalent, a proper PCB guy would probably know, but you might need to find an old timer to understand the question. Or try googling of course!
Regards
Mike
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Roger M Unwin
Sent: Tuesday, June 19, 2012 3:38 PM
To: [log in to unmask]
Subject: [TN] DH 99 Bakelite laminate
Hi TechNet,
Does anyone know if DH 99 Bakelite laminate is still available, or what a modern equivalent might be ?
The drg that specifies it is dated 1973, and is for an Antenna of some type.
Many Thanks
--
Roger M Unwin
P+M Services (R) Ltd Tel : 01706 815212 Fax : 01706 818636
http://www.p-m-services.co.uk
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