hole size for tight fit

Advert

New Replies

Report Bug

Help/FAQs

hole size for tight fit

This topic has 16 replies, 10 voices, and was last updated 5 August 2011 at 07:23 by pgrbff.

Viewing 17 posts - 1 through 17 (of 17 total)

Author

Posts
4 August 2011 at 07:18 #72824
pgrbff
Participant
@pgrbff
I need to drill a hole through a bar that will be a tight fit on a 6mm motor shaft. Will a 6mm shaft go into a 6mm hole drilled on the lathe? The shaft will be secured using a grub screw.
Advert

4 August 2011 at 07:18 #5608
pgrbff
Participant
@pgrbff
4 August 2011 at 07:28 #72825
JasonB
Moderator
@jasonb
Boring would be best using a small boring bar, reaming next option down, then plunging with a slot drill and finally at the bottom of the list drilling.

Have you actually checked the shaft, it may be a nominal 6.00mm but actuallly measure a bit less.

J
4 August 2011 at 07:31 #72826
pgrbff
Participant
@pgrbff
I dont have it yet. will wait and see. Hope boring bar not too expensive!

Thanks
4 August 2011 at 07:52 #72827
Clive Hartland
Participant
@clivehartland94829
At the size of 6mm then a reamered hole is fine. The grubscrews (two) should be placed at 90 degrees apart.

If cone point then dimple the shaft.

This is the way its done on the Theodolites I work on.

Clive
4 August 2011 at 08:58 #72828
pgrbff
Participant
@pgrbff
Can I use a hand reamer on the lathe? Or is it better to remove the item and hand ream after drilling?
4 August 2011 at 09:29 #72829
Gordon W
Participant
@gordonw
Check the motor shaft dia. first. If it is 6mm, drill 5.5mm, then 6mm, should be good enough for your use. You don’t need a good reamed finish, just an accurate hole.
4 August 2011 at 10:31 #72831
ady
Participant
@ady
I’ve read that if you stone the “wings” at the outer cutting edges of a drill tip this desharpens and stops the flutes “opening out” as drilling progresses, and gives a more accurate hole.

I’ve only needed to try it seriously once and it made the drill a tight fit as it drilled the hole, so oil is definitely recommended, even for a short hole.
4 August 2011 at 10:32 #72832
Pat
Participant
@pat
Simply use a hand reamer having pre drilled the hole under size. Use the tapered portion of the reamer to slowly open up the hole trying the fit on the motor shaft as you go. Stop when the motor shaft just enters the hole being reamed being careful to ignore and radius on the end of the motor shaft. The small taper on the hole should ensure a nice press fit.

Use the hand reamer not a machine one in the lathe tail stock chuck is ok but turn the work by hand not under power as you only want to remove a smidgen of metal. I would use ‘Locktite’ or similar rather than grub screws unless removal at some future date is envisaged. as this will not add extra out of balance to the motor shaft.

Do not use a taper reamer as these are designed for use with matching taper pins not to bring the hole to a dead size. Check the motor shaft size against the reamer’s designated size as the motor shaft may already be under size to suit stock pulleys etc.

Regards – Pat

PS a boring bar for a 6mm hole is very delicate.

Edited By Pat on 04/08/2011 10:34:10
4 August 2011 at 10:39 #72833
pgrbff
Participant
@pgrbff
The only other question is a general one on brands and quality. I’m not sure I’m allowed to ask but as these tools will probably only be used once, I don’t often need to do any machining but have a lathe and mill at my disposal, I would prefer not to spend a fortune. Are brands like Festo, Guhring and Dormer, which I have often seen, good enough quality for what I need to do?

I would normally buy the best I can afford, but when it’s only going to be used once it can get very expesive.
4 August 2011 at 11:04 #72835
David Clark 13
Participant
@davidclark13
Guhring is top quality.

Dormer is ok, I once broke a dormer tap and using a carbide drill to remove the tap, it drilled like it was butter.

Not familiar with Festo.

regards David
4 August 2011 at 13:03 #72840
Phil P
Participant
@philp
I think he may mean “Presto”

Phil
4 August 2011 at 13:17 #72845
pgrbff
Participant
@pgrbff
I do, I mean Presto, Festo are woodwoking. Presto any good? Better or worse than Dormer?
4 August 2011 at 13:18 #72846
Roderick Jenkins
Participant
@roderickjenkins93242
As an amateur I would regard Presto and Dormer as premium brands. For the tasks mentioned in this thread, the lower cost imported tools as sold by the advertisers on this web site will, I am sure, be perfectly satisfactory.

Rod
4 August 2011 at 13:26 #72847
David Clark 13
Participant
@davidclark13
Presto used to be ok.

Not used them for 30+ years.

regards David
4 August 2011 at 16:51 #72857
HasBean
Participant
@hasbean
Try Here , always found them very helpfull (usual disclaimer etc)

Paul
5 August 2011 at 07:23 #72896
pgrbff
Participant
@pgrbff
Thank you all for your help.
Author

Posts