Is there a term for this? (cutting by drilling holes)

[dorin]

Some of the live steam books I have read suggest cutting parts of the frame by drilling a series of holes outside the line you wish to cut..then do the cutting.

Is there a term for that??

Thanks,
Mike

[Errol Groff]

Chain drilling is the term I associate with the technique. Drill are easily re-sharpened and less expensive than end mills.

[dly31]

Somewhere I read that drilling removed the most metal per horsepower hour of any machining process. I do lots of 'chain drilling' to make cutouts in materials of a suitable thickness.

[tornitore45]

Is the only alternative to curved cut if you do not have a band saw or a plasma cutter. I have used serial drilling many times. I have a tinned down hack saw to separate the pieces and use a cold chisel where the saw can not go.

[SteveHGraham]

One of the most useful lessons I've learned is to try to get stock in sane sizes. I can't tell you how many times I've taken a huge piece of metal and turned half of it into chips just to get a small part!

[dorin]

Thank you everybody.

It still looks like it requires patience...but I have a feeling if I put a template over what I wanted to cut, the holes
likely help you "stay within the lines" too!

[tornitore45]

A template would work but is a lot of work to make just for one piece.
For straigh cuts scribe a line clear from the final dimension to include the drill radius and any slop you feel to add for the ability to stay on the line when drilling at fast repetition. Walk a compass set fro drill dia + some meat + some allowance for slop, punch mark heavy and drill away.
For circular cut if the center is known and accesible you can use a compass to mark the envelope but for complex curves I aproximate with straight lines.
This operation call for many holes and is boring (pun not intended) is easy to get careless break out into another hole, seize and get hurt. No matter how repetitive the job is, do not loose you concentration.

Last piece I used this method was the crankshaft for my twin cylinder model.

[dly31]

I find that drilling every other hole and then going back to drill out the in between parts works a little better for me. You can adjust the center and bit size if needed for a decent cut. Leaving a fair web between holes prevents breakout and is usually fairly easy to finish with a very narrow chisel and hammer.

[seal killer]

All--

For an arc, center the work piece under the spindle mounted on a rotary table also centered under the spindle, offset the mill table the radius of the desired arc plus half the diameter of the drill bit plus a few thousandths to allow for drilled hole oversize syndrome and drill the necessary holes then clean it up however you want. Side milling is my usual method. (Don't change the setup. Replace the drill bit with the appropriate end mill and then change the radius to reflect the diameter of the drill bit and the few thousandths left for clean up.)

I've performed this procedure all of ONE times. However, I have a job on the mill right now that will add two more arcs to that count. I figure that will make me experienced.

--Bill

[steamin10]

I have rejected chain drilling. On things like a small locomotive frame or an engine beam, cut from flat, I rely on drilling start and stop holes as big as I can fit, on the drill press, and resort to my band saw to get to the start holes and drop most of the material. I dont sweat the shapes, and once opened up, resort to a hand hacksaw, where I have thinned the blade, grinding away the back to nearly half dimension. Once hooked into the part, I can turn the saw like a jewelers saw, only making short work of 1/4 and 3/8 material, and easily turn for a contour, not available to a band saw. Light cuts and a good feel are the order of the day, as the blades can break easily if forced. Patience is the key, going for good instead of speed. Since my mill is small, most of my cutting is done with larger bits, and smoothing edges is much more enjoyable than trying to hog, and destroying the cutter.

Just what I do, your milage will vary.

[refinery mike]

Just a suggestion but I have found that a good sabre saw with propper blades can be used instead of chain drilling, especialy in internal cutouts where a band saw can not get. It used to be sabre saws were only sutable for wood, but I have a Bosch and have used Dewalt at work and they can do a pretty good job of cutting a slug out to allow for future machining.

[wlw-19958]

Hi There,

If you have a blade welder, you can use a bandsaw to make
internal cuts.

Good Luck!
-Blue Chips-
Webb