How do I measure an adjustable reamer?

[NickG]

When I reamed the bore for my flame licker with an adjustable reamer I was having trouble measuring it. Last night, when setting another reamer up for the same job on poppin, I realised why. There are only 5 cutting edges, I assumed for some reason there would be 6, so I was measuring across the cutting edges with a mic. Of course, this gives the wrong reading as they are not opposite each other!

So I did it by measuring the cylindrical section in between the blades, then measuring from that on one side to the extreme of the blade on the other, then add on the thickness that the blade protrudes. Is that the right way to do it? It seems very fiddley but can't think of another way.

Nick

[spuddevans]

There are only 5 cutting edges, I assumed for some reason there would be 6,

I dont know the answer to your question, but I do remember reading somewhere that countersinking bits are often made with an odd number of cutting edges because odd-numbered cutting edges tend to chatter less. Maybe that's why your adjustable reamer has only 5 cutting edges.

( hows that, I didnt answer the question you asked, but I did answer the question you didnt ask  )

Tim

[ieezitin]

Nick.

I know what you mean.

I have done this before, put a known size piece of material in the lathe.

Put an edge finder on it and get your measurement. Now with an indicator  get a reading where you are. Either with a dial indicator or a DRO you know where you are.

Put reamer in chuck and find the edge and bingo.

All the best   Anthony .

[kellswaterri]

Hi Nick, I will try to explain what I remember of using 5 bladed adjustable hand reamers, this is roughly 50 years ago...firstly, you do not measure the reamer to set it, a reamer is picked to go in to the bush or bore that has to be enlarged...the bush must be a ''one piece'' no splits as must be any bore you are cutting, otherwise the reamer blades will catch in the split and set up a chattering or very poor finish...if the bore needs to be enlarged by up to 10 thou. then pick a reamer that when the blades are pushed in to their smallest setting , the reamer wil fit neatly into the bore, then proceed to expand the blades a little takeing about 2-3 thou per timefor each cut...remember measure the bore Not the reamer...keep winding the blades out a little at a time until you get to the required size...some folks used a loose guide to help keep the reamer true, also lots of light oil to clear the ships...hand reaming with these reamers is an acquired skill and I do hope I have explained this sufficiently to let you get on with the job...
All the best for now and good luck,
                                              John.

[ieezitin]

Nick.

Misread your heading   AJUSTABLE    Reamer.

I thought you just had a unknown size reamer.

What I  do is go under size then very gradually increase the size being very careful and check my bore size every time I  make a pass.

I first make one pass and note the size. Rotate the screw about 10* make another pass and note the difference. This way you should get a feel on the expansion of the reamer.

Its hard to do you only have .005.

Hope this helps.      Anthony.

[NickG]

Thanks guys, I bored the hole 5 thou undersize, it actually measured 6 thou under. I tried setting the reamer to 5/8" last night with the mic and I haven't tried reaming it yet but the first bit of the reamer went into the bore, would there be a built in taper on this type of reamer to help get started? At the end of the day, the size isn't critical, as long as I don't start getting too large and making the wall thin. I purposely left the cooling grooves a bit shallower incase things go wrong and I need to go up anyway though. I will just do maybe 3 2 thou cuts until I get an acceptable finish etc.

Thanks again,

Nick

[websterz]

Thanks guys, I bored the hole 5 thou undersize, it actually measured 6 thou under. I tried setting the reamer to 5/8" last night with the mic and I haven't tried reaming it yet but the first bit of the reamer went into the bore, would there be a built in taper on this type of reamer to help get started? At the end of the day, the size isn't critical, as long as I don't start getting too large and making the wall thin. I purposely left the cooling grooves a bit shallower incase things go wrong and I need to go up anyway though. I will just do maybe 3 2 thou cuts until I get an acceptable finish etc.

Thanks again,

Nick

Especially so with an adjustable reamer, the first part in the hole does all the cutting.  Rather than make a full depth cut only go .100" or so deep and then check the size. Adjust and repeat, going an additional .100" beyond the previous test cut to insure you are getting a full bite with the reamer.

[kellswaterri]

Hi Nick, yes, there is a slight inbuilt taper, which means that you must ream right through the bush or bore...take small cuts, about 2 thou. at a time...as long as there are no slits or cuts in the bore length for the blades to fall into you will be ok...remember that these reamers have loose blades ''renewable''  and they are controlled by the adjusting nuts at each end which have an female taper fitting over the ends of the blades and holding them in position, one for adjusting out and one for in ''large or small diam.'' I usually pick a reamer spec. midway between the size I am going to cut, wind the blades down in diam. by slackening the nut and pushing all the blades in to seat in the slots of the reamer then bring the other nut down to lock the blades into position... if the leading part of the reamer enters the bush/bore by 1/2---1'' check all nuts are nipped up front and back and apply some oil then proceed to ream right through...the taper is only a few thou so I reckon on about 3-4 thou. per go.
All the best ,
                 John.

[NickG]

Thanks for the advice guys, I will set my reamer up to do just that. Luckily it is mid size.

Cheers,

Nick