Hobbymat mill

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Hobbymat mill

This topic has 8 replies, 3 voices, and was last updated 14 November 2014 at 18:23 by Bubble.

Viewing 9 posts - 1 through 9 (of 9 total)

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7 September 2014 at 10:50 #162896
Stuart Osborne 5
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@stuartosborne5
The morse taper in my mill is not running true, it is perfectly clean. I have dismantled the head and I can not see how to remove the spindle fron the bearing sleeve. Any ideas please, tried gentle encouragement with rubber hammer but no joy.
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7 September 2014 at 10:50 #17502
Stuart Osborne 5
Participant
@stuartosborne5
Removing spindle
7 September 2014 at 16:12 #162933
Neil Wyatt
Moderator
@neilwyatt
Hi Stuart,

What are you doing to measure the error and how big is it?

Have you checked the bearings are not loose?

Neil
7 September 2014 at 17:07 #162936
Stuart Osborne 5
Participant
@stuartosborne5
Thanks Neil. It is about one thou. Out. The tip of a small drill is a blurr. Bearings are nice and tight. A friend gave me this mill and had tried to ream the taper but his lathe was not rigid enough and the tail stock just vibrated when he put the reamer in. ( he can't remember how he got the spindle out of the bearing sleeve!) I have found someone with a heavy lathe and will try reaming again if I can get the spindle out of the sleeve. I am not sure whether these posts go automatically, I can't find a 'send' button, that's why you might have two copies of this.
7 September 2014 at 17:26 #162940
Neil Wyatt
Moderator
@neilwyatt
The Schlesinger limit for the internal taper of a mill is 0.0004" or just under half a thou.

Measuring the tip of a drill or bar held in a drill chuck won't give you an accurate impression, as you are very unlikely to have a drill chuck with accuracy comparable to,. let alone better than, the taper. You should measure the accuracy of the taper by poking a DTI inside.

With that level of error, the reamer will almost certainly just follow the existing hole anyway, it really should be ground.

Neil
7 September 2014 at 17:38 #162942
Stuart Osborne 5
Participant
@stuartosborne5
Have tried tapered drills too. It is definitely the taper that is out. If necessary we can re grind it or make a new spindle If I can't sort this out but the problem remains of how to get the thing out of the bearing sleeve. I am using the mill for clock making. On the up side it drills holes halfway between imperial and the metric equivalent!
18 September 2014 at 18:01 #163886
Stuart Osborne 5
Participant
@stuartosborne5
FIO Neil Wyatt. Grovel grovel. It seems it was the bearings. They have been re packed and the taper cleaned and there is now less than half a thou run out. To remove the spindle and bearings there is a left hand threaded bearing cover beneath the spindle flage. There are two stud holes in the bearing cover accessed through two corresponding holes in the spindle flange. Thanks for your interest.
14 November 2014 at 18:04 #169587
Stuart Osborne 5
Participant
@stuartosborne5
I have just dismantled and re-bushed a hobbymat mill gear box. If anyone has any questions about it please ask away while I remember!
14 November 2014 at 18:23 #169589
Bubble
Participant
@bubble
Hello Stuart

Some years ago on my Hobbymat mill circa 1980 vintage, I bored out the original MT1 to MT2. I used the Chaddock method (in his Quorn book) to support the spindle in its own bearings in the lathe steady. As far as I remember I used an HSS boring bar as the spindle was not too hard. I can't remember if I set up the topslide or used my taper-turning slide (as designed by Chris Heapy). The conversion was (and still is) very successful. The Hobbymat head is now mated to my Tom Senior mill.

The spindle design is very good and why they were made with only a MT1 bore puzzles me.

Jim
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