Hi all,
We have a job where we have to ream four .2496" holes -.0001 +.0004 on the mill. The material is aluminum and the holes are .5" deep. I have read almost all the posts about reaming and have gotten conflicting answers on almost everything, so much so that a lot of people completely give up on reaming all together. I don't have much experience with reaming so here is a couple questions.
1. Should I use a free floating holder on the mill when reaming (like a tapping holder) or just stick the reamer in a fixed collet and indicate the reamer concentric? I am assuming the free floating reamer would allow the reamer to follow the hole better.
2. Some people said using oil can cause the hole to go oversize so you should instead use coolant. Others say you should use oil or WD-40. What is the correct answer? I am assuming coolant would be able to keep the part more cool than brushed on oil would but I don't know.
3. Should the reamer rapid out of the hole when finished cutting or should it feed out of the hole with a G01 move at the same feed rate as going in?
4. I read that you should leave .01 - .012 (sometimes as high as .031) in the hole for the reaming operation. Other people say you should leave about .004-.005 in the hole for the reaming operation? Which one is correct?
5. Should I use a carbide reamer or high speed/cobalt reamer? I am guessing the carbide reamer will cut a more precise hole, but it is aluminum so I am assuming a high speed reamer would do a good job. Enlighten me here.
6. For speeds and feeds, a lot of people say 1.5x the feed and half the speed of your drill. Is this true? What speeds and feeds should I run? I would think it would be depended on if you are using a HSS/cobalt or carbide reamer.
7. What size reamer should I buy for the job? Should I buy a reamer at the .2496 size or should I buy a reamer a couple tenths under in case it cuts big?
8. Should I countersink the hole before reaming to get rid of any burr at the top of the hole?
9. If a reamer has more flutes, does it cut more precise? Will a six flute reamer at .2496 cut to size better than a .2496 four flute reamer?
I wanted to say that we haven't done a whole lot of reaming (we ream holes occasionally) because my dad (owner of the business) likes to ream with drills. He used to ream a lot of holes with reamers where he used to work years ago and says sometimes they are more trouble than what they are worth. What he does is spot/center drills, drills the hole to a size about .010 from the nominal size, then runs the final size drill in the hole to get the final dimension. It usually lands us +-.0005 or closer. The final drill is typically a high end double margin 140 degree drill. Or if he wants a straight hole, sometimes he will spot/center drill, then rough drill, then run an endmill in there to straighten the hole out, then run a double margin 140 degree high end drill to get the final size. Is this something you all do?
Thanks,
Chris
We have a job where we have to ream four .2496" holes -.0001 +.0004 on the mill. The material is aluminum and the holes are .5" deep. I have read almost all the posts about reaming and have gotten conflicting answers on almost everything, so much so that a lot of people completely give up on reaming all together. I don't have much experience with reaming so here is a couple questions.
1. Should I use a free floating holder on the mill when reaming (like a tapping holder) or just stick the reamer in a fixed collet and indicate the reamer concentric? I am assuming the free floating reamer would allow the reamer to follow the hole better.
2. Some people said using oil can cause the hole to go oversize so you should instead use coolant. Others say you should use oil or WD-40. What is the correct answer? I am assuming coolant would be able to keep the part more cool than brushed on oil would but I don't know.
3. Should the reamer rapid out of the hole when finished cutting or should it feed out of the hole with a G01 move at the same feed rate as going in?
4. I read that you should leave .01 - .012 (sometimes as high as .031) in the hole for the reaming operation. Other people say you should leave about .004-.005 in the hole for the reaming operation? Which one is correct?
5. Should I use a carbide reamer or high speed/cobalt reamer? I am guessing the carbide reamer will cut a more precise hole, but it is aluminum so I am assuming a high speed reamer would do a good job. Enlighten me here.
6. For speeds and feeds, a lot of people say 1.5x the feed and half the speed of your drill. Is this true? What speeds and feeds should I run? I would think it would be depended on if you are using a HSS/cobalt or carbide reamer.
7. What size reamer should I buy for the job? Should I buy a reamer at the .2496 size or should I buy a reamer a couple tenths under in case it cuts big?
8. Should I countersink the hole before reaming to get rid of any burr at the top of the hole?
9. If a reamer has more flutes, does it cut more precise? Will a six flute reamer at .2496 cut to size better than a .2496 four flute reamer?
I wanted to say that we haven't done a whole lot of reaming (we ream holes occasionally) because my dad (owner of the business) likes to ream with drills. He used to ream a lot of holes with reamers where he used to work years ago and says sometimes they are more trouble than what they are worth. What he does is spot/center drills, drills the hole to a size about .010 from the nominal size, then runs the final size drill in the hole to get the final dimension. It usually lands us +-.0005 or closer. The final drill is typically a high end double margin 140 degree drill. Or if he wants a straight hole, sometimes he will spot/center drill, then rough drill, then run an endmill in there to straighten the hole out, then run a double margin 140 degree high end drill to get the final size. Is this something you all do?
Thanks,
Chris
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