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Reamer size questions

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mark costello 128/11/2019 14:43:08
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621 forum posts
12 photos

Would Locktite work?

Dunc28/11/2019 14:53:51
133 forum posts

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

PANAGIOTIS EVRIPIOTIS29/11/2019 09:59:21
19 forum posts

@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.

PANAGIOTIS EVRIPIOTIS30/11/2019 15:03:28
19 forum posts

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

Neil Wyatt30/11/2019 15:41:43
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Posted by PANAGIOTIS EVRIPIOTIS on 30/11/2019 15:03:28:

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

Dusty30/11/2019 15:51:13
484 forum posts
8 photos

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.

Sam Stones30/11/2019 21:46:07
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788 forum posts
308 photos

Did you intend that pun about the drift Dusty? cheeky

PANAGIOTIS EVRIPIOTIS01/12/2019 10:49:24
19 forum posts

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.

Versaboss01/12/2019 13:03:03
460 forum posts
51 photos

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

Versaboss01/12/2019 13:09:04
460 forum posts
51 photos

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

Tony Pratt 101/12/2019 13:18:47
1339 forum posts
5 photos

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

PANAGIOTIS EVRIPIOTIS01/12/2019 19:14:49
19 forum posts

@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

Mike Poole01/12/2019 22:19:55
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Moderator
2841 forum posts
67 photos

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

Versaboss02/12/2019 13:04:44
460 forum posts
51 photos

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

PANAGIOTIS EVRIPIOTIS02/12/2019 13:35:42
19 forum posts

@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

Martin Kyte02/12/2019 13:53:18
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2154 forum posts
38 photos
Posted by Dunc on 28/11/2019 14:53:51:

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

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.

PANAGIOTIS EVRIPIOTIS02/12/2019 13:56:19
19 forum posts

@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

JasonB02/12/2019 15:43:25
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19505 forum posts
2131 photos
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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.

Neil Wyatt02/12/2019 17:18:06
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Moderator
18404 forum posts
718 photos
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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

Neil Lickfold02/12/2019 17:46:03
650 forum posts
102 photos

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

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