Reamers essential?

[Piecat]

Being new to the hobby, and new to this forum, may I start off with a question?

I have a brand new fully equipped Taig Metal Lathe with just about all the basic tools except reamers. As there are so many diiferent plans available for small engines with reciprocating pistons (air, steam, gas, Stirling, etc.), is it absolutely necessary to use reamers for a half-decent model? If not, what other methods are used for close fits?

Thanks

Piecat

 

[PerryRT]

First of all, welcome to the hobby!

Reamers are handy and relatively economical if bought "as needed". What I might suggest is rather than buying a set, try to get a few common sizes in HSS reamers of good quality and go from there (the pure carbide ones are way more than you need to bother with right now)

For example, maybe just get 1/4" and 3/8". Enco has "made in USA" ones for about $10 each.

The problem you may have with a Taig (I had the same with my original Sherline lathe) is that normal "chucking" (machine) reamers are LONG. That 1/4" one I recommended above can be ... 6" or more? So you can run out of bed length if you're not careful. There are "short" reamers available (but at higher cost.) (I also finally broke down and bought a set of stubby drills - same reason).

There are other ways to make things work. A lot depends on the material you're working with, of course, but you can bore something out, or use a plug charged with abrasive, or try half a dozen other things I haven't thought of, probably. Depends on your patience and requirements for precision.

The other thing is that you have to realize that as long as the piston and the bore match, the final size isn't all that critical (within reason), so if the plans call for a 0.245 bore and you have a 1/4" reamer.... make the corrections you need to match the equipment you have, and work with it.

Honestly, that's part of the fun of this hobby. You get to take a plan and figure out how to make it work for your equipment. This is called fun!

 

[PerryRT]

Oh, and if noone told you this... Never never never turn a reamer backwards (counterclockwise.) Will ruin it in a heartbeat.

Don't ask me how I know that. :-\

 

[mzetati]

for the little I know, reamers are not intended to be used to get cleanly finished holes, nor straightened, their purpose being bringing a hole to size within stated tolerances.
Not being in a production environment, they're not an absolute need.

That said, they're handy.

Marcello

--
Bores and shafts can be lapped to a smooth finish, using homemade tools.

 

[Omnimill]

Welcome to the forum Piecat, I think Perry has answered your question!

It really helps sometimes if we know where you are when answering questions so have a look at Marvs post near the bottom of this page for how to do this if you want to. Some folks won't reply if they don't even know what country you are in!

http://www.homemodelenginemachinist.com/index.php?topic=10130.0

 

[crankshafter]

Piecat.
Welcome to the forum.
If you are in need for a reamer, get you some drillrod/silversteel and make your self D-bit -reamers to suit your small lathe. Do a search on the web and you will find the how to make them.
I have made a lot of them and they work great.
Have a look here: http://www.homemodelenginemachinist.com/index.php?topic=5251.0

CS

 

[lensman57]

Being new to the hobby, and new to this forum, may I start off with a question?

I have a brand new fully equipped Taig Metal Lathe with just about all the basic tools except reamers. As there are so many diiferent plans available for small engines with reciprocating pistons (air, steam, gas, Stirling, etc.), is it absolutely necessary to use reamers for a half-decent model? If not, what other methods are used for close fits?

Thanks

Piecat

Hi,
It is not a questuion of necessity. If the holes are large enough that you could use a boring tool and you know how to get a decent finish then you do not need reamers. It is highly unlikely though, that you could bore a true 5mm hole 30mm long in which case you need reamers to bring the drilled hole to size. Hand reamers are cheaper but could only be used for a through hole as they have a long taper compared to a machine reamer which is considerably more expensive. So the advice is to buy as needed after studying the plans. With reamers as with other tools you get what you pay for.

Regards,

A.G

 

[Dave G]

Hi Piecat, reamers are a handy way to size a hole but it will leave you with a hole that is less than round. When I have a hole that needs to be round, like a cylinder bore, I always bore the hole with a single point tool. Boring will give you a better surface finish, more control of size and it will be as round as the runout of your headstock. A bored hole will be easier to finish by lapping or honing.

If I have a predetemined size I need to finish at I normally will make a couple of plug gages before boring. These will be a couple of .001
in size difference so I can sneak up on the finish size. If the hole has to sized to a very close fit with the mating piece I will hone it before making the male piece. I have the luxury of having a sunnen honing machine to finish my holes but a simple lap would be just as effective.

I keep reamers around for making holes for dowels pins and for litttle else. In the Tool&Die trade, bolts aren't used to position components, they are use for holding components together. Positioning should be done by dowel pins, keys or shoulders.

Yes, reamers are good to have around but they are limited in their use. I would much rather have a selection of boring bars at my disposal. When boring, tool pressure is important to be aware of. When I bore a hole to size, the last 3 or 4 cuts I make will be of the same depth. This gives a more uniform pressure on the tool. If you practice boring you will notice that if you run the boring tool back thru the hole a second time at the same setting it will normally take a little more off. Thats the difference in tool pressure having an effect. All tools deflect away from the workpiece a little, controling this deflection or managing it is the secret. Use as large a boring bar as possible for rigidity. A good suface finish on the tool helps a great deal.

Reamers allow a quick way to finish and size a hole but in this line of work the quickest way sometimes isn't the best way. Before you setup that casting for boring, practice on a piece of scrap that is the same material as your workpiece. Get a feel for what is going on and make corrections on the practice piece.

I have been doing this stuff for close to 35 yrs now and I will still use a practice piece if I'm not comfortable. I hate to scrap anything and I have learned to take as many steps as neccesary to finish the job. I wish you luck in getting started in machining and the forum is here to help. Dave