Cutting Internal Jarno Tapers

[4VRGJ03]

Good Afternoon Everyone! Does anyone have experience in producing an Internal Jarno Taper? I received a drawing which is calling out this taper on a hole. I have attached a piece of the drawing so everyone can see. I can't attach the whole drawing  but the part itself is a fork like bracket and one of the cross holes has this taper. My question is how do I go about machining this taper? Is there a special tool? Does it have to be ground? Can it be turned? and finally how to check the taper? Do I have to buy a Gauges? I have a CMM but mabey I need a Go/No-Go Plug gauge?

Not sure how to approach this. I appreciate everyone's time and efforts. The Material is Titanium

[crazy^millman]

With threads always check with a no-go and go gauge. I have seen to many false readings from CMM's for threads. I have never seen this call out before I would go back to your customer and ask them to provide you with the specification for this thread or the standard you need to manufacture to.

[Wildcat]

A Jarno taper is similar to a MT taper except a different angle. Its not a thread. They make reamers for most tapers and you can check it will a ball drop.

[4VRGJ03]

Bingo! I didn't know they sold Jarno Reamers and your right I can check it with a spherical ball. Thank-you very much. I can now quote this job!

[RaiderX]

learn something every day, thanks all

[crazy^millman]

2 hours ago, RaiderX said:

learn something every day, thanks all

Me as well.

[4VRGJ03]

Alright gentlemen, So I figured this out.... I think. If you want to use a reamer you need to purchase a custom reamer for this job. According to my quote this will run you about $625US to about $825US each reamer. I have about 30 pieces to cut from titanium.  Due to the size of the bore diameter you cant get the reamer in carbide at an efficient price. Which means how many titanium pieces can 1 reamer cut?? Because of this uncertainty and because of the risk associated with scrapping a block of titanium thats about 12" long 7.00" wide and 6.0" thick using a reamer, you need to grind this taper. The risk is lower and the price is about $350Canadian each piece with a non recurring charge for the fixture as well as the gauge used to check the part. A ball drop may work but your better off with a gauge that will sit flush to the end face when placed in the bore. If the taper is wrong the gauge will either sit too high or sink to deep.

So the next time you have a fair size taper to cut in an expensive piece of material you may want to consider grinding it. Reaming titanium with this size and this type of taper is whey too risky. Before you master the reaming process you may scrap 1 or two pieces, and what if one of the flutes of the reamer you use chips off during reaming. 

Better to grind. In the long run it's cheaper and alot safer (providing the grinder knows what he is doing). This I Guarantee.