Reamer size questions

Would Locktite work?

Surprised that no one has mentioned machining your own D-bits.

@mark costello 1

Nope it wouldn't because I need to be easily disassembled with a mallet and punch otherwise I would opt for a press fit and avoid locktite.

@Dunc

I do not own a lathe otherwise I could theoretically make my own toolmaker's reamer although I do not have the knowledge to do that yet and also not the time to experiment on it.

Hello again everyone, I am having some second thoughts regarding reamer sizes for different kind of fits.

Just to get a good grasp could someone explain in the case of a shaft that is .250 with a tolerance of +- 0.0002, what the size of an H7 reamer would have to be to achieve a tight fit? (to be able to disassemble with a punch and mallet

One last question would be if anyone know of any vendors that sell hardened stainless steel dowel pins, maybe from 416 or 440c steel. So far in Europe I see that the standards are either soft stainless steels or non stainless hardened steels.

Thanks for your help everyone

As you have an accurate shaft, you actually want an H6 reamer to get a 'medium drive fit'.

Neil

Panagiotis, the problem you have is that if you require the pins to able to disassemble from the plate, after a few times that this occurs the fit will become less. You will eventually get to the stage when the pins will fall through the hole, well that might be a little extreme but you get my drift.

Did you intend that pun about the drift Dusty?

Ok I will rephrase my question. Let's consider the following scenario.

I have a very accurate shaft as I mentioned above (+-0.0002 tolerance) of 1/4 inch.

I need to find the appropriate H7 reamer to get a tight fit therefore it has to be a bit undersized. The tolerances of H7 reamers are available online and I know for a fact that this scenario can be achieved.

So the questions is what should be the size of that H7 reamer to get that fit. As I said I will go undersized, my problem is how much I should buy.

@Dusty

I see your point. When I said that I want the user to be able to disassemble it, I meant if he has too and to my mistake I didn't mention frequency. This disassembly will happen very rarely if ever therefore I will avoid what you said. Also I don't go for a press fit because I want the user to have the option of removing the staff.

As far as my knowledge goes, a H7 reamer has a positive tolerance from the nominal value. So you would hardly get a 'tight fit' (whatever that is) with such a reamer. I don't understand why you don't jump on the metric reamers in 1/100 mm steps. I could name easily 2 or 3 shops in Switzerland which send tools anywhere in the world.

About fits in general, there is a nice utility called ModelEngineer's utilities (www.alanjmunday.info). Enter your values and see what you need.

Kind regards.
Hans

Seeing just now that my link above does not work. But the utility can be found here:

https://modelengineersutilities.software.informer.com

Kind regards,
Hans

6.34mm reamer at H6 tolerance should work for you, in theory hole would be 6.34 to 6.349 mm. Best to do a trial run on a piece of scrap first.

Tony

@Versaboss

Firstly, I would really like to use just metric but in order to do that I need to understand the theory. How lower should I go to get a tight fit in the scenario mentioned above if my reamer is exact and has no tolerances. If I get a number for that then I can make my own calculations, account for tolerances etc. and see what I am going to buy to achieve that.

By the way give me please the names of these two shops.

P.S. I can download the resource from your 2nd link but it seems broken. It fails to extract

@Tony

That's the answer I am looking for to get an understanding

You could make your own toolmakers reamer to any size you want, cheap and easy to make. Google will supply the how to make.

Mike

Dear Mr. Evripiotis,
well I will do my best. First, to my big grief I had to discover that the M.E. utilities stopped to work correctly. Some of the buttons are ok, but the 'Limits and Fits' are now unusable. It is the latest version, and is on my computer (W.10) since umpteen years. I tried to load them on my Laptop (W. 8.1), but I could not unzip the file... Some of the buttons show now a black background, and the 'captions' are invisible, and 'calculate' does nothing.
It would be worth an own thread, why a program suddenly can stop working correctly.

Now to the reamer problem.
One address I know is the Brütsch, Rüegger toolshop:

brwtools

The other is the manufacturer Re-Al:

Re-Al

Hope I could help you a bit.

Kind regards,
Hans

@Versaboss

You certainly helped a lot, thank you for that info.

Could you make a suggestion regarding size please so I can make my conversions and order metric reamers.

Say that I have, as I mentioned before, a shaft of 1/4inch +-0.0002" and I want to achieve a tight fit, meaning that I will need for example a set of pliers and some force to remove or a mallet.

Now I can easily find for example H7 reamers who according to standards have a tolerance of +0.00059" in the range of 6mm to 10mm(if I am reading correctly).

In order to achieve such a fit with the above circumstances what should the reamer size be in inch or metric?

P.S. I know I am probably not using the term "tolerance" correctly but you get what I mean.

Regards,

Panos

How about making your own D-bits?

(There you go)

;O)

or stone the corners off a 1/4 inch drill and use that. It will drill undersize when following a pilot hole.

@Martin

I on't have a lathe to do that, so I will need to find precision ground hardenable steel rods to do that. Also with my experience and the machines that I have I am not sure I can make as accurate tools as I need

6.33mm or 6.34mm would be the most likely but there are so many other variables that can affect what size the reamer actually cuts that you will have to do a few test cuts. The final size will be affected by one or more of the following.

Pilot hole size

Material being cut

Dry or lubricaed

How the reamer is held (fixed or floating)

What machines you are using eg a drill press will likely cut larger than a milling machine, handheld drill even more likely to be oversize.

Condition of reamer, it will wear with use.

What you conside a push fit may be another mans press fit.

Another idea - use a hand reamer and just use the tip, which is tapered, experimenting until you get the fit you want.

ideal for locating pins.

Neil

You can make a lap, and lap the od of the reamer smaller to get it to the diameter that you require. This works very well with machine/chucking reamers. Lapping a hand reamer does not work so well however.

Neil