5/8ths reamer how to?

[Speedy]

I have to ream my engines crank case. I purchased a 5/8th's spiral reamer as I have wholes in the crank case for carburetor and cylinders

I see that my instructions say and show a reamer to be put in between the work piece and tail stock center, what I dont understand is how will the reamer "ream" out the hole if nothing is stopping it from spinning?
a tailstock chuck makes sense but a live center?

hopefully someone can shed some light on this.

 

[Jasonb]

The safest way is to use a large tap wrench or failing that a spanner on the square end of the reamer. Then with the lathe spindle LOCKED rotate the reamer by hand while gently winding in the tailstock quill. Rotate in the same direction when removing the reamer.

It can be done under power but you need to know what you are doing.

J

 

[lensman57]

Hi Speedy,

I too have a Taig lathe and a variable speed dc motor on it ( Sherline ).

Have you got a hand reamer or a machine reamer?

If it is a hand reamer then it is self explanatory just use tons of lubricant and take slow and steady, if it is a machine reamer then I don't think the little Taig has enough power to ream a hole that size, you might be better off using your X2 mill in the low range to try and ream the hole, it has to be perfectly centered of course.
Alternatively use a large tap wrench as suggested in other post.

Regards,

A.G

 

[Speedy]

my reamer does not have the square end.

I am using my neighbors machine for the job its a big harrison lathe.
JasonB is it really that hard? is my idea wrong that you use the tailstock chuck? not a live center.

 

[Brian Rupnow]

The conventional way of running a machine reamer, whether spiral flute or straight flute, is to lock the reamer in the tailstock CHUCK and put the peice to be reamed in the headstock CHUCK. Use lots of oil and a slow feed. A hole has to be drilled first (unless there is a hole already there) about .015 to .020" undersized from the reamer diameter. Straight flutes are used in a hole which has no other features. Spiral reamers are used in a hole which has a "feature' in it, like a keyway. The reamer sets stationary and doesn't move except right to left and is fed by hand. The part revolves in the headstock. You do not use a live center in the tailstock.---Brian

 

[Jasonb]

Tailstock chuck is OK provided it is true.

J

 

[Speedy]

thank you Brian and Jason.
I will see maybe if I can bring it back for a hand reamer, if not I will do it on the harrison.
the harrison spins slow on low speed so I think I am fine with that.
will see how it all goes

 

[Speedy]

just curious before I use my machine reamer, is their any benefit of a machine reamer to a hand reamer four our hobby ?

I was going to exchange it for a hand reamer but maybe I should ask you all first.
also thinking the hand reamer may be more expensive

 

[lensman57]

Hi Speedy,

Besides the obvious a machine reamer has a very short lead taper at the head compared to a hand reamer, think of this as a bottoming tap V a taper tap, therefore it is the suitable for reaming blind holes such as a cylinder in model engineering. A hand reamer has a very long lead taper comparitively and is only suitable for through holes. Hope this explains some of the differences.

Regards,

A.G

 

[Speedy]

hi A.G I was under the assumption they made straight reamers like the machine reamer but with a square on the back to use a wrench or tap handle?
im very new to reamers, hefty prices so want to get one that will work best in the long run.

 

[kf2qd]

They do, but a large number of users just chuck them up in the tailstock and go for it. Amazing what a lazy guy can do if he puts his mind to it...

I have a 1/4 hand reamer that I don't think has ever been used by hand. A hole was drilled and the then the reamer was chucked in the same setup and the hole was finished, on size and excellent finish.

I have used a hand reamer with a tap wrench when i was running the reamer back through to make sure the hole was clean after test fitting a part...

 

[Maryak]

IMHO, machine reaming is better done and more accurate, (provided the drilled hole is true), if the reamer is supported by a centre and fed into the hole with the tailstock. The reamer is prevented from rotating by a tap wrench or spanner. The method is known as floating reaming. When the ream is finished, the tailstock is removed and the wrench is used to withdraw the reamer whist continuing to rotate the headstock in the same direction used for reaming.
Using a chuck or morse tapers to hold the reamer in the tailstock introduces and magnify's any tailstock errors in both the y and z axes.

Not all reamers have a centre hole in the rear end, but all machine reamers do.

Hope this helps

Best Regards
Bob

 

[Speedy]

my machine reamer does have a center hole, but nothing to attach a spanner or tap wrench.
wouldnt using a tailstock center still have the same tailstock errors since its attached at that point still.

 

[Maryak]

wouldnt using a tailstock center still have the same tailstock errors since its attached at that point still.

Speedy the short answer is No.

Why...........because the reamer is not attached, merely supported at the back end by the tailstock. The business end of the reamer floats and as such is guided by the hole it is reaming. If the reamer is held in the tailstock then the business end cannot float and so it will try to cut in line with the tailstock.

Reamers only remove the last few thou/0.01'smm from the diameter so if it doesn't float, it can be out by a few thou/0.01'smm. If the tailstock is off centre the reamer or the work bends to try and get back on centre and the hole ends up oval. Again we are only talking small numbers so it depends on the desired result.

Hope this helps

Best Regards
Bob

 

[kvom]

All my reamers are very long compared to their diameters and have a fair degree of flex. I've never had an issue reaming using a tailstock chuck. That said, my tailstock is quite well aligned with the spindle, and the tolerances in most engines are not likely to be affected.