drilling & tapping cast iron

[Paul B. Cresti]

I am going to be mounting a power feeder to my shaper. Can anyone give some insight on drilling and tapping a cast iron top?

[Keith Outten]

Paul,

Cast Iron is very soft and easy to drill, consequently it is also easy to tap. Power feeders are generally very heavy and you need to be concerned about the moment arm so you would be wise to find an area in the top where you can drill though and use large diameter washers or a matching plate on the bottom side to spread out the load instead of tapping the holes. I doubt that a few threads in the thin section of a cast iron top would be sufficient to handle the load and not crack the top at some point in time when you needed to apply a large load for a large piece of material.

[Rob Russell]

Paul,

Another option is to buy one of the Felder power feeder mounting brackets. They bolt on to the side of the machine (you drill and tap holesin the sheet metal for that). The top of the bracket is predrilled for the Felder feeders, which are just relabelled Maggi Steff units.

The bracket mounts on the back of the saw. If you're looking at the back end, to the left of the slider is where the bracket mounts. The brack is 2 piece and hinged, so the shaper can be flipped over (hanging upside down) an out of the way when you don't want to use it. One of the Felder owners invented a device with a gas spring that counterbalances the weight and makes it easy to flip up and over.

The brackets should be available in a white/light gray which should look OK with the MM equipment.

Rob

[John Weber]

Paul,

Depending on how big a feeder you have, you should be able to either drill and tap or use through bolts. I used through bolts for mine. Cast iron drill easy, I used a small bit for a guide hole and then the larger size I needed. A sharp bit makes quick work of cast iron. I also use a little oil as a lube for both drilling and tapping. Finally, I mounted the feeder base in the shaper extension wing for several reasons. It makes missing the ribs easier, and keeps the main top hole free.

John

[Kurt Aebi]

Paul,

I like the thru-hole idea a little better than the Drill & Tap method, due to the brittleness you can get sometimes with Cast Iron threads. Unless you have a large, coarse thread that can have at least 5 turns of thread, I would shy away from that method. The other advantage of the thru-hole method is it will allow for some error in your hole spacing or allow you a little fine-tune adjustability. If I were to get a feeder, I would either use the heavy magnetic mount or drill thru-holes.

You may do as you like, these are just my opinions from meny years of working with cast iron as a toolmaker with a punch-press stamping company in New Hampshire - before I got my Engineering degree and moved from the shop to an office.

[Paul B. Cresti]

Guys,
thanks for all the input. My shaper is the MM T50n and the power feeder is the Steff Maggi 2048. Both machines are big. The cast iron top is at min. 1/4" thick. The spot where I woul mount the feeder bracket staddles a rib. It is in the back left corner of the shaper as you stand it front. I like the thru-bolt because it allows for some error and I would hate to marr my beautiful top. I am also considering some type of moveable cart system that allows me to permently mount the feeder to and allows me to "move" the feeder to different machines if needed. Any other thoughts???

[Jim Dunn]

If your going to hand drill I'd use a drill bit just a pinch smaller than recommended. Hand drilling is generally the cause of over size holes. Oversize holes equal not enough thread shoulder to hold something tight. Drill and thread dry No Lube! Clean out holes if blind.

[Jason Sanko]

Through bolt it with washers for maximum load distribuion on the top. Cast iron is brittle even to a 1/4" thickness. It does drill nice, like said above use a lubricant. I use common WD-40 when I drill it. Instead of strings like a steel it will produce smaller "chips" of metal due to the randomness of grain structure of the metal. Use a guide block of some sorts when drilling to get an acurate hole, or drill hole one size smaller and then enlarge with proper drill bit. I would not thread it too easy to strip out in my opinion when it really counts like a power feeder.

[Rob Russell]

For purposes of mounting the bracket, straddling a rib doesn't sound like a problem to me. I'd think that having the feeder mounted to the T50's base will give you a more stable base than a rollaround cart would. I suppose if you came up with a way to lock the rollaround cart to the shaper base, effectively securing it so it can't budge, that the cart idea would work just fine. Part of the issue there is the leverage the feeder will put on the cart when the feeder is hanging over the shaper and pushing down on stock.

[Rob Russell]

Drill and thread dry No Lube! Clean out holes if blind.

Why dry? I've always been told to lubricate, especially when tapping.

[John Shuk]

You could try to contact an iron worker near you and get a Magentic drill press to drill the holes as well. My friend used one to drill holes in the I-beam through the center of his house it worked pretty well. As an artchitect maybe you know a guy?

[Paul B. Cresti]

I just remembered it is a 3 phase feeder along with my other machines, so the cart idea is not so good for my small shop and cabling limitations. I think the best idea is to thru bolt it and used some big washers/plate underside the table.
Should I use the black coated bolts to avoid any galvinic (sp?) action or just the regular silver machine bolts?

Yes, I probably could find a Iron worker but, hey he needs to make a living too and guess what us Architects/woodworkers ain't rich (not yet at least) & we have bills up the wazoo

[Jim Dunn]

Cast iron is my nature "soft". In all my yrs. as a tool room mach. I never lubricated cast iron to either drill or tap. Even in production runs, making thousands of cast iron bell housings for the tractor industry, did we ever set up a machine using lube as factor in drilling or tapping.

As to the lube itself. Most novices use an oil based lube. It has a tendency to bind the chips in to the lands of the tap. Having lands full of chips make no room for more chips. Consequently additional materials bind and cause the tap to break.

If you insists on a lube find a water soluable type and spray on using a mister. No need to flood with lube.

[Rob Russell]

Learn something new every day! Thx.

[Michael Perata]

Paul

I mounted a Delta Power Feeder on my CU300 Smart by drilling and tapping (5/16" IIRC). I used the webbing cast into the table as a stiffener by rotating the drilling pattern so I drilled next to the webbing and not through it.

To make sure I got the holes perpendicular to the surface I used a General drilling guide.