Jig Borer

[Darren]

Could someone please tell me the difference between a jig borer and a milling machine, cos I've been wondering for quite a while....and it's making me restless....

[John Stevenson]

Well have sit down, a scratch and a glass of milk and behave yourself..............

John s.

[Darren]

Ok.....

[John Stevenson]

Jig borer.

Same layout and build up as a mill but differ in subtle ways. Made for very, very accurate location and boring of holes.
Spindle usually quite light, bearings more suited to axial load than radial as all the thrust from boring is down.

leadscrew very accurate and often had some form of compensation to take out errors in the screw.
Usual one was a strip of hand scraped steel running at the side of the screw that carried a follower, this in turn would move the zero mark for the dial in places where the error of the screw needed to be compensated.

Many had early forms of optical measuring or at the least a dial gauge and a set of measuring sticks so a direct reading could be taken. A decent jig borer like a BCA will make a good mill for small model making but some of the purists and flat earth society will throw their arms up in the air.

A thing of the part nowadays given the accuracy of modern CNC's.
.

John S.

[Darren]

Ta....that certainly clears that one up.....

[Darren]

One on Ebay right now.....looks like it could be a nice addition to have permanently set up in the workshop.....but I'll have to pass as like most room has to be very carefully allocated.

I'm just a sucker for old tools 

http://cgi.ebay.co.uk/BCA-bench-top-jig-boring-milling-machine_W0QQitemZ250477639133QQcmdZViewItemQQptZLH_DefaultDomain_3?hash=item3a51a175dd&_trksid=p3286.c0.m14

[bogstandard]

Darren,

That one looks in rather bad condition.

A good second hand Mk2 will usually command a price of between 1000 and 1500 squid.

I was given an almost brand new Mk2 from where I used to work, and it had all the extras with it, all the collets, boring head etc, plus cabinet stand. I found it would be too limited for normal milling, but if you wanted to do some very high precision small stuff, then it would be ideal.

If I remember rightly, 3/8" was about it's max tool capacity, and that was really pushing it to its limits, as normally there is a belting system at the back, looks like it is missing on this one, and that would limit you to the amount of cut it would take.

I swapped mine out for my surface grinder and loadsa cash.


John

[Darren]

Interesting....

I think at that value a surface grinder would be a better allocation of space and funds to us types....

and whatever else the change takes your fancy...funny init the value of some things....