what cutter to use.

[sunnybob]

I'm making a marble solitaire board that will use 1/2" marbles, but I cant get a good cut for the marbles to sit into.
I used a router bit with 2 blades and circular shape, but it chattered like crazy and has left a very ragged and slightly lopsided hole. I am cutting into teak.
What should i use please?

 

[novocaine]

1/2" carbide ball burr?

not cheap but would do the job.

or look at why you are getting chatter, it's possible that if it's a 1/4 shank you are getting movement as you plunge.

 

[hawkeyefxr]

I would have though a router was way to fast for marble. A burr may well be the way to got using lots of water.

 

[sunnybob]

The cutter is for the teak base, in which the marbles rest.

I must admit I used the cutter in a drill press so that I could align the holes properly. Hadnt considered machine vibration. I shall look into that.

 

[Eric The Viking]

Ah - belay the dril press idea (below) then. shame :-(

It's a jolly good question, Bob.

You're not alone in getting poor results from those semicircular grooving cutters. :-(

They strike me as a poor design, as the middle bit is hardly moving at all (same with the V-grooving ones). As a consequence there can't be a "correct" speed for them. You're also cross-cutting, and going with AND against the grain, all in one go. I do get approximately reasonable results, but only when I've been actually grooving with the grain (in softwood, admittedly), and they're still prone to burning and tearout. Simply plunging has never really worked with a router bit. And to get it looking nice, I find I usually have to start in the middle of the slot and work to the ends, taking fast-shallow nibbles. But I usually do it by dropping-on on the RT, rather than anything handheld, and for things like cill drip grooves the rounded ends are in the waste, anyway.

I wonder if you could "hog out" some of the shape with either a conventional twist drill (in a press), or possibly a countersink. otherwise the idea of a spherical rasp sounds like a good-un. You might also try your actual router cutter in your drill press, as it may give you better speed control, and certainly better accuracy and depth control.

I wonder also if you might get better results by cutting deeper and then planing/sanding the surface back to achieve the shallow indentations you're after.

Keen to hear if there is a good solution (there must be!) as those cutters have always frustrated me.

 

[novocaine]

put it in the router. much stiffer than a drill press and turning a lot quicker. I think we have found the problem you've got more run out on a drill press and much further to travel not to mention movement between the quill and the mast, the mast and the table, the table and the vice......... you get the idea. stick it in a router and run it fairly quickly.

 

[loftyhermes]

If I remember correctly, the old Craft Supplies used to sell a ball end dill bit just for this.

 

[Phil Pascoe]

a ball end dill bit???

You will not have any success using a router cutter in something so slow as a drill press - as anyone who has ever tried router cutters on a Shopsmith (other brands available) will tell you. You might need to design templets and use a bush. Tedious.

 

[Woody2Shoes]

The trick to avoiding (potentially dangerous and certainly very unhelpful) chatter using a hemispherical router cutter like this: http://www.axminster.co.uk/axcaliber-ro ... k-ax828929 is to use a guide bush and circular template - and then to use these so that you're moving the cutter around the template in a (very small, and only just bigger than the diameter of the actual cutter) circle. In this way you avoid trying to "plunge cut" with a cutter that isn't really designed for it, and you're always cutting "uphill" (assuming you move clockwise) which is safer and more predictable all round (pun intended).

The other part of the trick is to do it in multiple passes.

There's at least one video on Youtube of someone (maybe WoodWhisperer?) doing this very successfully.

Cheers, W2S

 

[sunnybob]

Lots of theories to consider.
But i think the drill press was a mistake because its a very basic press that holds a standard mains drill with electronic speed control and I know it wasnt set to max rpm.
The hole isnt really a hole, its more of a depression, so no chance of removing wood with a drill bit and then smoothing.
That axminster cutter is very deep, to get a 12 mm diameter I have to buy a 30 mm depth when I dont need much more than 5 mm.
Again, this was only a try out, so buying a thirty quid cutter just for a one off kiddies toy is a non starter.

I might just leave it as is, its mainly for the grandkids to play with when they visit, then it will be forgotten.
If I think about it I will utube it and see what other people do.

 

[Phil Pascoe]

If it were a decent drill press it wouldn't make any difference - they're just not fast enough. The cheap Trend 1/2" set (someone found it for £25 not many days ago) has two different sized core box cutters in it.

 

[ColeyS1]

How about a forstener bit and put some felt in the bottom of the holes ?
Coley

 

[Racers]

Make sure your router bit is a plunge cutting bit with a blade that goes across the middle of the bit.
I would use the router to cut the holes.

As long as the hole is smaller than the marble it will sit in it.

Pete

 

[monkeybiter]

I second the idea of using a template and a guide bush in the router. It's what is used in cheap signwriting kits [I have one] with a round ended bit and works fine in the crappy router I use for it.
You could use a piece of ply the same size as the board and drill lots of guide holes or have one piece/guide hole and just move it to where it's needed, the first would be better and easier though.

 

[cedarwood]

If its any help I have made six of these using my triton router fitted with its rectangular base plate and a bull nose bit fitted.
I marked all depressions with a cross in pencil directly on the wood (no template) using a large tri square, set the router to cut the first one, put a clamp guide with measurements on across the board, set the depth guide on the router then holding the base plate tight against the clamp guide with my left hand and with the router set to full speed plunged it down slowly to depth with my right hand.
Once the first line across the board was complete then all I did was move the clamp and repeat for the next line.
Hope this is of some help

 

[sunnybob]

I dont have any router bushes.
I do have a router mounted on a sled. i could hot glue the board down and then plunge the bit in.
I have enough spare thickness I could smooth the top and start over.
I found a utube vid that showed the guy making holes (dents) with a 45 degree counter sink bit. It looked horrible.

It might have to be put on the back burner though, 'er indoors has woken up to the fact my woodworking hobby isnt just about bandsaw boxes and I can build garden stuff as well, so now I'm involved in a small pergola to shade the adirondack chairs i just made. (sigh)

 

[Hemsby]

Ball nose slot drill :idea:

 

[sunnybob]

Ball nose slot drill :idea:

Not at £48 a time, thanks.

 

[Rorschach]

You need a centre cutting ball nosed end mill. I use them all the time and they will drill a very neat hole as long as your set up is rigid. Drill drill would be essential.

 

[Rorschach]

Ball nose slot drill :idea:

Not at £48 a time, thanks.

They can be had a lot cheaper than that, you don't need the really high quality ones if you are not doing production work. My preference is solid carbide, pricey but they last me years.