filing cat iron

Hi there

i am not really a beginner but I think this is the best place to start this thread.

Does anyone know the best type of file to get through the skin on cast iron, ordinary with coarse cut, tungsten carbide grit or diamond?

I am asking because I need to open up a square hole in a casting so machining is a non starter!

Drill it with carbide

File the edges square

Masonry drills have carbide tips if you don't have carbide drills

Cast Iron is a doddle with the backgear engaged.

Strap the casting to the saddle?

Edited By Ady1 on 24/03/2012 20:04:36

The problem is that the casting has been cored so there is already a square hole through it, just undersize. I need to get through the skin on the inside of the hole to enlarge it to its final size.

aaaaahhh....

How big is the casting in simple terms

How big is the square hole and how long/deep

I haven't done anything like that but the other guys will dive in once they get a few details.

Machine a datum surface on the outside, then use a shaper with a carbide tip??

hmmm...

Edited By Ady1 on 24/03/2012 20:24:03

Diamond files will shift anything and are quite cheap, so they're what I would use.

Martin.

The casting in question is the rear axle box for a 2in Burrell Gold Medal. It is 2 1/2 x 1 3/4 inches and the hole is just over 3/4in square x 1in long, to be opened up to 7/8in square to accept the rear axle tube. There are two of them, both identical, so I have to do it twice!

Never had this scenario but in general cast iron is easy to file but there is likely to be some crud left in the hole from the casting core so I would start with an old file. Don't assume that there is a skin--might be but there again maybe not.

I agree with Martin diamond files will cut almost anything but they are slow to use, one other type of "file" you may hav seen at the ME exhibitions is the ones with carbide bonded onto a piece of sheet metal and they are considerably courser than diamond files--can't recall the trade name though.

Cheers John

Answer.... an old one! an old warding file should do. it will remove a skin, and if there isnt a skin it wont suddenly remove a large amount of cast iron, as cast iron is surprisingly easy to file. i file all the spokes on loco wheel castings, so am aware of the problem

Hi

More than likely there will be a "skin" but this is usually very thin once this is removed cast iron is a dream to file compared to some other metals. Built a 7.25g loco which had lots of casting some years ago and did not use anything special in the line of files. As my old dad used to say elbow grease my lad... Good luck with the burrell and keep all of us posted as to progress.

Bob

I think what JohnF may have been alluding to are Permagrit tools, do a google search, there are uk stockists and although I have no personal experience, I have had accounts of their durability and excellent performance. These are Tungsten Carbide, not Diamond and are available in varying grades. I have used TC tile files on cast iron and they do remove significant amounts of materiel so I would suggest that PermaGrit tools would perform at least as well.

If you go down this route, please let all know of your experiences.

regards

CB

Take the skin off as much as possible with a carbide burr or small grinding bit in a Dremel or die grinder then file out the corners and tidy the faces with a file.

You say the part cannot be machined but why can't you mill out to the 7/8 square and then just file the corners if you don't want an internal radius. You could also knock up a tool like a slotting head and plane the corners out. I think filing alone will not give a good sliding face unless you are very good at filing or use a rest.

To help people see what you want to do, this is the part in question

J

Edited By JasonB on 25/03/2012 08:16:43

have none of you heard of a Black and Decker Powerfile?

chriStephens

Success!

I used diamond files to break the skin, after that it was plain sailing. Now i've just got to do it again for the second one!

Just for the record, I checked permagrit's website and they only do one large flat file which is 38mm wide so no good in this instance.

Thanks to all for the plethora of advice.

I hope you wore a face mask, or are you blowing black gunge out of your nose now?

Joey

Martin just get a 6" second cut Vallorbe flat file, easy. Many places do them.

If you go for the square files they have rounded or radiused edges so cant get a sharp edge.

What i would have said if seen this thread is centre existing square hole and drill out just under 7/8", plain sailing then.

Square holes relatively easy, just keep an eye on what your doing.

How did you hold the cat and did it yowl much???

(Tongue in cheek!!)

donhe7