Eagle Surface Grinder Model 3 Rebuild - Spindle Refurbish

My MK3 is almost as described by Tony on lathes.co.uk/eagle
with one difference, at the back there are two deep grove ball bearings.


He writes:
Sized imperially, the ball races consisted of two opposed angular contact ball bearings behind the wheel with a single deep groove ball bearing at the drive pulley (rear) end. Interestingly, if the angular contact bearings are dismantled (they push apart) an owner reports that they can be revived by polishing the races lightly with diamond paste, fitting new balls and lubricating with ordinary lithium grease.

The spindle of my variant runs in two angular contact bearings, each pair in back to back (DB) arrangement. The preload adjustment is not clear, need to do more research here. The bearings are of imperial dimensions ID 25.4 OD 63.5 ( 1" x 2.5" ). 

The spindle assembly is pulled out to the front, there is a hole in the middle to restrain the shaft from rotating.

Once out, the bearings pull apart and the balls measure in at 10.30 mm since this is an imperial sized bearing my thinking is this was probably a 13/32" ball. (10,31875mm ). Initial measurements of the races ID and OD confirm this.

I could not find a suitable new replacement for the Bearings.
The replacement is still manufactured under the following names from R&M, SKF and some other brands.

RMS8    MJ1 - Deep Grove
AMS8    MJT1 - Angular Contact




Since the bearings show significant wear, there are two options under consideration.

1) Use 7006 bearings 30x55mm and machine new sleeves to fit the 1" shaft and 2.5" outer seat.

2) Do what  Tony describes. Order new balls, polish the races and see what I get.

Eagle Surface Grinder Model 3 Rebuild - Planning

The surface grinder is made up of the following precision guided parts, a vertical column, a knee, a cross slide saddle, and a horizontal table.

The machine is build in a typical column knee setup as seen in horizontal milling machines.
The column has two parallel and one perpendicular planes.
The knee has two perpendicular planes.
The cross slide has two perpendicular and two parallel planes
The horizontal table has on plane

Starting at the biggest surface first and then working my way back seems to make the most sense. This includes all surfaces on a specific component. ordering the components by guide ways surface area yields this sequence.

• Vertical Column 2 x 800x50mm flat+ 2 x 800x30mm Dovetails
• Knee  2x300x50mm flat + 2x300x50 dovetail + 2x400x50 flat + 1x400x50 dovetail
• Table 2x 800x50mm flat + 2x 800x50mm dovetail
• Cross slide 2x 200x30 flat + 1x200x30mm dovetail + 2x400x30mm flat + 1x400x30mm dovetail
• Gib's with two surfaces 60Deg, 3 x

Planned steps and sequence:

• The table was surface ground to be used as a template.
• Build a holder for all three angular flat gib's 
• Scrape in all flat and angled surfaces of the gib's so they can be used for templates later.
• Build indicator jig for measurement, geometry and dimensions to provide 3 point contact to measure all surfaces in need of scraping
• Scrape Column front side flat, using the feed table, this will preserve the original machined surface on the center of the column. indicator jig should provide 3 points of contact on the original machined surface and two on the dovetail surface, to measure dovetails.
• pre scrape knee vertical slides with straight edge or gib as template.
• align vertical and scrape horizontal slides of knee on surface plate
• pre scrape knee right side dovetail using the knee's gib as template.
• Fit knee on column and scrape column dovetails to match,
• finish scrape knee vertical slides.
• pre scrape cross slide flat ways and align on surface plate
• pre scrape dovetail ways using the gib's as templates
• scrape knee side on cross slide using the knee as template, align to column.
• scrape table side of cross slide using the table as template align to column and knee
• use the knee with planing attachment on the feed table to machine a recessing center column, 
• would give a nice sharper like finish, maybe when I have energy left at that point.

Eagle Surface Grinder Motor Rewiring for 3Phase 220v operation

The motor is a Gryphon by Brook Motors Ltd.
Rating 1.25HP
380-440V 3 Phase
2850rpm

I use 220v single phase, thus had to replace the motor or figure out how to run it in 3 phase delta mode.
Luky a bit of googling gave me the encouragement, to convert it.

http://madmodder.net/index.php?topic=7773.0

His star point is located on the other side but nonetheless I found the star point.

Eagle Surface Grinder Model 3 Rebuild - Assessment

Before rebuilding my machine I like to plan the entire rebuild, and simulate different aproaches in my head, to make sure I do not start at the tail end of the project. Here it helps to write down my thought process to keep track.

Firstly I do an assessment of the wear surfaces to establish where what needs to be done.

On the surface grinders the feed (x) axis does the most traveling, for standard flat grinding job, the feed axis will travel the length of the material x 2 for each in-feed (y) advance, and the down feed (z) axis will travel one depth of cut for complete feed , in-feed cycle.  Assuming maximum material to be removed on a surface grinder is less then 1mm, and the in-feed is 0,5 and down feed is 0,1. And stroke length is 150mm and table length is 300mm. Then the total distance traveled for full table work piece to remove 1mm material is:

feed (x) ( 150mm/ 0,5 ) x (300mm+300mm) = 180 000mm = 180m
in-feed( y) 10 x ( 150mm + 150mm) =  3000mm = 3m
down feed (z) = 10x 0,1 = 1mm

With this in mind you will have to spin the feed hand wheel 190 times, and if a feed cycle takes 10seconds it will take half an hour to complete the job ( hand wheel is 300mm diameter) most parts are not that big, but still a long time to stand there.

Perhaps the reason for full automatic grinders, and why I consider automating the machine.

Anyways, so I expect to see most wear on the feed axis, then in-feed, and then down-feed.

Below the measurement, the maximum wear on the feed ways is 0.582 rear and 0.809 front.

The down-feed guide ways on the column, are worn on the bottom side to about 0,03mm. Due to the cantilever effect of the knee, I expect the dovetail guides on the back to show similar wear in the center portion.

Tales of a stubby Tailstock

The Colchester Chipmaster Tailstock consists of a base and top casting, the sliding surfaces are worn by about 0,435.  The lateral adjustment is guided by a inverted v slot on the front side, now my plan is to use brass shim stock to raise the total height by 0,435.  a simple way of doing the calculation for the 45deg v slots ( isosceles triangle) is by dividing the required height by the square root of 2 or
1,414213562

This gives 0,30759145mm shim thickness.