Thread: Drilling jig help

Originally Posted by MrFixIt

Hi

That's easy enough

Use two pieces of angle iron at least 6mm wall thickness, fastening one angle iron inside the other as shown in the VERY ROUGH sketch.

Hi MrFixIt,

I will need to digest what your are suggesting and get my head around it. You have put a lot of work and thought into this and I thank you for doing that. Have you used this design before?

Regards

STEAM

Hi Metal Head
Yes you are right in what you are saying. The 1.5mm deep passes to cut the slot will leave a series of steps. This is why a Slot Drill must be used for this opperation. A standard end mill would create terrible grooves in the sides of the metal if used for this job. A Slot Drill will cut exactly to the diameter of the cutter. These cutters have only two flutes and form a perfectly balanced cutting "process". I much prefer these cutters to any other kind for machining a slot, especially for a keyway in a shaft.. For the job in question, the "stepping" is very minimal to almost unseen. I chose to do the slot in mutiple passes as cutting the full depth to clean the sides up, using a slightly smaller cutter, could pose a safety problem for "Steam" as he is a newbie to machining and is begining at the bottom of the ladder. A Tungsten Carbide cutter of the kind I have does a fantastic job on steel, aluminium, brass, many other metals and also plastic. Regardless of the cutter material, for best results, the cutter must have zero rake on all cutting edges. This means a cutter with straight flutes and it must be used for safe machining of brass. There are other factors that can affect the quality of the cut face. These are, rigidity of the milling spindle, trueness of the cutter, flexural stiffness of the cutter which is also linked to the length of the flute protruding from the collet, cutter diameter and cutter speed. If you get the opportunity to use a TC Slot Drill, do try it out. The Slot Drills get their name from having only the two flutes, just like a drill.
Many thanks for your reply.

Kody

Originally Posted by STEAM

Hi MrFixIt,

I will need to digest what your are suggesting and get my head around it. You have put a lot of work and thought into this and I thank you for doing that. Have you used this design before?

Regards

STEAM

Hi Steam

Give me a call if you have any questions

I am happy to help, but it didn't take all that much effort on my part. It took me much longer to write about the jig than it did to conceive the idea. I came up with the design in about five minutes after reading your post. I have not used this method before, but it is really an extension of, or alternative method of clamping used on many machines. A split collar or similar is clamped by tightening a bolt, causing the collar to tighten around a shaft. The same result could have been obtained by drilling the holes in a single piece of angle iron and then splitting the holes with a slitting saw. The top half (of the angle iron) would then be fastened to the bottom half with bolts, the material removed with the slitting saw would allow the two halves to "squeeze" together thus clamping the shaft. My design has moved the split to a different position

As the saying goes, there are "many ways to skin a cat" each method has its benefits and drawbacks. I am not saying that my way is the best, just different. I think the jig I propose would be easier to make and much quicker and efficient in "mass producing" your parts. There is less setup time to produce more items.

A slot drill as proposed will certainly do the job but I believe there is much more table movement and manual intervention required using a slot drill. There is also a need for TWO setups for EACH PIECE as you will need to change the axis of the part (for EACH part). Mill the slot, change axis drill the hole, repeat for each part. This method will be made more complex if the slot and the hole are different sizes, as the tool will need to be changed for each operation on each part.

(sorry Kody, but...)To create the "two headed" part for Kody's jig also requires extra lathe setup time if you need to face the insides of the smaller diameter. This of course may not be a problem if you have the time

If you can setup and use two lathe stops (saddle and cross slide) you can just turn down to the stops (diameter and length) and part off. Set up a piece of bar in the tailstock to use as a stop when moving the material through the chuck to make the next part, this way you only ever have to do the main lathe setup once then keep turning and parting off

Call me if you don't understand.

Originally Posted by kody

i chose to do the slot in mutiple passes as cutting the full depth to clean the sides up, using a slightly smaller cutter, could pose a safety problem for "steam" as he is a newbie to machining and is begining at the bottom of the ladder.[/color]

now i can see where you were coming from

must be used for safe machining of brass.

very true kody. I would also say it is definitely needed when drilling perspex, or you will end up damaging the item. Thanks for the explanation mh


kody

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