By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

Colchester student 2500/harrison m300 feed gearbox cams

Cam orientation

All Topics | Latest Posts

Search for:  in Thread Title in  
damian noble27/03/2019 20:11:45
avatar
167 forum posts
15 photos

Hi all,

Posting here for a bit of help as a search of the internet hasn't turned up what I'm looking for.

When I got my Colchester student 2500(metric 6mm leadscrew) the gearbox was seized which is the same as the M300 problems. I stripped out the four cams carefully numbering them up after a clean with solvent to remove the old oil and residue.

Unfortunately I didn't get back around to reassembling the gearbox until last weekend after a gap of 5 months the solvent which was left on the parts had dissolved my permanent marker and now I'm guessing which gear is supposed to make in each of the 8 positions on the rotary knob?

Looking from the back with the lead and feedscrew to the left and cam 1 to cam 4 follower left to right. I have the 8 gears (again left to right) meshing in with the selector knob position as follows 1-2-7-8-3-4-5-6. Would like to confirm this is correct?

The selection was vague and taken me some rotating about with the selector to make the gears line up in each of the detent positions.

I have tried the harrison m300 Yahoo group but it is very quiet on there.

Many thanks for the info and help in advance guys

Damian

FMES27/03/2019 20:48:31
608 forum posts
2 photos

Ahh, the benefits of hindsight and photos..

Is this any good? **LINK**

Regards

damian noble27/03/2019 21:02:25
avatar
167 forum posts
15 photos
Posted by FMES on 27/03/2019 20:48:31:

Ahh, the benefits of hindsight and photos..

Is this any good? **LINK**

 

Regards

Agreed and lesson in not trusting 'permanent ' marker again. Scribed line across the delrin cams will be the way to go.

Seen the link above but the photo's and videos on the gearbox don't show the cam as it's hid behind the selector forks and also they dont mention how they relate to each other.

I have seen one video on you tube that states selection 1 has the first gear made. No further details.

I'm looking at a last resort of a mail to the 600 group to get some detail.

Edited By damian noble on 27/03/2019 21:03:20

Bazyle27/03/2019 22:54:41
avatar
6956 forum posts
229 photos

Are you on the Harrison Yahoo group?

I analysed the gearbox a few years ago while considering making one for another lathe. I'm struggling to understand my spreadsheet but here goes.

Edit - photo is from back so reverse my left right below.

From the input side the selector blocks (the blocks in the photo) go in the order, wrt the dial numbers:
(4,3,) (6,5,) (2,1,) (8,7) with any block not in play in the middle neutral position.
Another description is the left block moves to the left in position 4, to the right in position 3 otherwise in middle neutral.

therefore
position 1 meshes 33 to 24
position 2 meshes 33 to 27

position 3 meshes 22 to 20
position 4 meshes 22 to 22

position 5 meshes 22 to 23
position 6 meshes 22 to 24

position 7 meshes 22 to 26
position 8 meshes 22 to 28

Edited By Bazyle on 27/03/2019 23:00:21

damian noble28/03/2019 05:52:40
avatar
167 forum posts
15 photos
Posted by Bazyle on 27/03/2019 22:54:41:

Are you on the Harrison Yahoo group?

I analysed the gearbox a few years ago while considering making one for another lathe. I'm struggling to understand my spreadsheet but here goes.

Edit - photo is from back so reverse my left right below.

From the input side the selector blocks (the blocks in the photo) go in the order, wrt the dial numbers:
(4,3,) (6,5,) (2,1,) (8,7) with any block not in play in the middle neutral position.
Another description is the left block moves to the left in position 4, to the right in position 3 otherwise in middle neutral.

therefore
position 1 meshes 33 to 24
position 2 meshes 33 to 27

position 3 meshes 22 to 20
position 4 meshes 22 to 22

position 5 meshes 22 to 23
position 6 meshes 22 to 24

position 7 meshes 22 to 26
position 8 meshes 22 to 28

Edited By Bazyle on 27/03/2019 23:00:21

Hi Bazyle

I will have to check against the above if I get what you mean.

Yes I'm on the yahoo group but finding anything with the search function is hit and miss I find.

Damian

RobCox28/03/2019 08:31:54
82 forum posts
44 photos

Hi Damian,

I took my M300 gearbox off a couple of years ago when I gave the whole lathe a clean up and fixed broken/worn out bits. I took a lot of photos of the gearbox at the time in each of the selector positions.

I'll try and dig out the photos tonight and post them in an album. They may help you deduce which cam goes where.

Regards

Rob

damian noble28/03/2019 10:12:58
avatar
167 forum posts
15 photos
Posted by RobCox on 28/03/2019 08:31:54:

Hi Damian,

I took my M300 gearbox off a couple of years ago when I gave the whole lathe a clean up and fixed broken/worn out bits. I took a lot of photos of the gearbox at the time in each of the selector positions.

I'll try and dig out the photos tonight and post them in an album. They may help you deduce which cam goes where.

Regards

Rob

Many thanks Rob I can work with the info above but pics tell a thousand words.

Once I get it back together I will take a few pics and post them.to the harrison group.

Incidentally I've had to replace the powerfeed output shaft and bush (harrison manual 303056 and 303107 colchester numbers are different) as these were badly worn, luckily a friend turned these up for me. Not sure about the other phosphor bronze bushes in the box but probably some wear in those too.

Cheers all for the assistance

damian noble30/03/2019 22:15:09
avatar
167 forum posts
15 photos

Using the info above from Bazyle I have refitted the cam assembly and adjusted the selector knob so that it changes whilst lining up the gears fully. Had to file the flat slightly on the selector

The selector still needs the occasional jiggle but changes are a lot lighter and more positive.

As Bazyle said looking from the rear as most photos of the removed box are, the numbers are reversed from the input side.

So the positions on the selector are (7,8)(1,2)(5,6)(3,4)

Cheers

Damian

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
cowells
Sarik
MERIDIENNE EXHIBITIONS LTD
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

 

Donate

donate