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Back rake question
- Thread starter porthos
- Start date
Without the benefit of a detailed engineering explanation, I would offer this simple illustration. Try cutting a piece of wood with a square block vs. a sharp knife. The block will scrape wood and peel it provided there is enough force while the knife will effectively remove chip with much less force.
That said a router bit removes wood effectively with zero rake. The secret is the rpm is fast enough and the depth of cut is small enough that the chips are tiny. The same is true for a power planer but a hand plane has a 45º to 60º back rake.
That said a router bit removes wood effectively with zero rake. The secret is the rpm is fast enough and the depth of cut is small enough that the chips are tiny. The same is true for a power planer but a hand plane has a 45º to 60º back rake.
Pics of your holder and inserts please.
Would like to see the angle that the holder holds the insert at.
Also how the insert looks.
If a lathe tool or milling tool.
There are many geometries, so it's hard to know what is being discussed in general.
Would like to see the angle that the holder holds the insert at.
Also how the insert looks.
If a lathe tool or milling tool.
There are many geometries, so it's hard to know what is being discussed in general.
A.R. Warner RH tool holder:
Holder provides back rack, similar to other insert holders. While in theory you can use ARW T-15 HSS inserts in any appropriate tool holder, theirs are extremely well made. The advantages of their inserts are that they are HSS and can be sharpened on an oil stone. Their LH holder and takes inserts on the “back” end so you can make use of the extra edges for chamfering.
A.R. Warner Tool Kits
looks like both side rake and back rake on that pic.
Looks like the holder provides it.
Looks like the holder provides it.
Sorry, yes: RH tool holder good for turning & facing when set up square. That and my Eccentric Engineering Diamond tool holder are the most used.
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You have to get clearance from somewhere. Usually an insert with no rake is used with a negative rake holder to provide the clearance. The up side is that you can use all the cutting edges on both sides, doubling the insert life. The down side is negative rake increases tool pressure which could be a problem on less rigid machines. The inserts with rake already ground in are for use with neutral or positive rake holders. The up side is less tool pressure, the down side is you can only use the cutting surfaces on the top side of the insert.
goggle AR Warner co. to look at their products. my replaceable hss bits are parallel to the holder with no rake. for those of you not aware of the company; the hss inserts have 3 cutting edges and can be sharpened on a flat stone, no grinding
i can see the back rake in the holder in the picture. BUT, i have 8 holders and none have the back rake feature. my guess is that ar warner re-desined the holder. mine are around 12 years old. their company is less than 10 miles from me. someday i will make a visit. the pictures on their site show no back rake holders. but, i'll take another look