My LMS 5500 (SIEG XS2.7) -- History and Current Problem

BTW, I received a response from LMS regarding the 5500 vs 6500 mills. The only differences are the control panel and the belt cover. All mechanical components are the same.
 
CraigH said:
I also went with tapered roller bearings on the mini-lathe. Mainly due to installation considerations. Bearing manufacturers specifically warn against typical pressing on when installing angular contact bearings. I considered all manner of heating and cooling of components (bearings, spindle, headstock) during different stages of the operations.
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I polished the spindle just enough to ease the force needed to press on the rear bearing. Tapered roller bearings come in two parts and that also facilitated the operation.
 
Half the parts have arrived - that being the spindle pulley - and it's on the bearing and its top plate.

What's a good grease for the spindle splines? I have Sta-Lube Sta-Plex Extreme Pressure Premium Red Grease and Sta-Lube Premium White Grease on hand. No typical dark Moly EP right now but easy enough to get.

I would think the thicker the better as it's not a bearing.
 
Installed the spindle pulley with a molykote film and red grease. Also installed a new toothed drive belt.

Ran in the new belt for a few minutes. The new pulley is a better fit, but of course not a press fit (which would not be possible). But still some noise.

Got a stethoscope (should have started with that) and there does seem to be noise from the pulley bearing. Ordered the same (ABEC 3). More delays.
 
Back to the LMS 550 mill.

Replaced the spindle pulley and spindle pulley bearing with no significant change. In fact, got worse with 3/4 inch end mill in brass, a lot of vibration. The end mill was dropping down which I did not notice because I was watching the dials for depth of Y-axis cut, and my vision is considerably impair.

So more web searching. And the search came across a post here on HM back in Aug-Oct 2018 about a Grizzly X2.7 with issues setting fine-feed and vibration problems. Member "greenail" has a video about the Z-axis feed, and his issues were similar to mine.


After a few views and pulling out the parts for cleanup and lubrication in the right places (he appeared not to lube anything), I began to mostly understand the adjustment - mostly. Without being completely sure, I got the parts in and with some fiddling seem to have the eccentric body adjusted - certainly better than it was. It had been notchy in use and very free spinning like a propeller when disengaged. Now it only spins a rotation or two (perhaps the grease on the shaft), and seems more positive when engaged.

I was not particularly looking forward to a test. But I ran four modest cuts (two on each long edge of a 5 inch x 14mm AL), and it seems better now. Time will tell.
 
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Now with all the milling issues experienced by me (and member greenail) regarding cutting quality, noise, and vibration that are hopefully set right, the mill is out of tram again. These SIEG 2.7 mills are not very rigid - even bolted down and column-to-saddle bolts tight, pushing on the head registers on an DI.

A few questions on column attachment and tramming. First, what is the size of the allen key for the set screw between the column attachment bolts? They are smaller than 3.5 mm and larger than 1/8 inch, and I do not have anything between those sizes. I also wonder their purpose - I am thinking they are to tune the tram front to rear before tightening the bolts. And given the short distance between the bolts on either side, tram is affected quite rapidly as the bolts are tightened. The footprint of the column should have been longer (Y-axis direction).

EDIT: Forget my question on the allen head set screws. I looked them up on the LMS parts list - they are referred to as an M6-24 taper pin. Probably an assembly expediency function.
 
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CraigH said:
Now with all the milling issues experienced by me (and member greenail) regarding cutting quality, noise, and vibration that are hopefully set right, the mill is out of tram again. These SIEG 2.7 mills are not very rigid - even bolted down and column-to-saddle bolts tight, pushing on the head registers on an DI.

A few questions on column attachment and tramming. First, what is the size of the allen key for the set screw between the column attachment bolts? They are smaller than 3.5 mm and larger than 1/8 inch, and I do not have anything between those sizes. I also wonder their purpose - I am thinking they are to tune the tram front to rear before tightening the bolts. And given the short distance between the bolts on either side, tram is affected quite rapidly as the bolts are tightened. The footprint of the column should have been longer (Y-axis direction).

EDIT: Forget my question on the allen head set screws. I looked them up on the LMS parts list - they are referred to as an M6-24 taper pin. Probably an assembly expediency function.
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In my opinion I think a 3/4” endmill is a bit much for this class of machine.

The specs say 5/8” max, but I think that is more marketing speak rather than good practice.

Also factor in your depth of cut when side milling.
 
RaisedByWolves said:
In my opinion I think a 3/4” endmill is a bit much for this class of machine.

The specs say 5/8” max, but I think that is more marketing speak rather than good practice.

Also factor in your depth of cut when side milling.
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I have and use a 1.25" face mill that uses carbide inserts, on my mini mill. But, and it's a big caveat, I don't use very large DOCs with it: and it's mostly used on aluminum. I have used it on steel and my mill notices it, but does OK as long as the depth of cut is small, .010" or thereabouts.

Milling stuff with holes in it disturbs the mill enough to produce obvious variations in the surface finish around the hole so I try to use the tool before drilling holes into the work.

This is with a 500 watt mini mill and an R8 spindle.
 
RaisedByWolves said:
In my opinion I think a 3/4” endmill is a bit much for this class of machine.

The specs say 5/8” max, but I think that is more marketing speak rather than good practice.

Also factor in your depth of cut when side milling.
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Given my experience I cannot disagree. The machine is not particularly robust - notwithstanding advertising hype.

The project requires three 3/4 inch diameter arcs cut into the circumference of a 7/8 inch cylinder of 5/8 inch height, 1/8 inch deep - Effort V1 was unsuccessful with respect to intent. I might consider something like using a smaller end mill, setting X-axis travel limits, and traverse left to right (conventional milling) with each increasing Y-axis depth of cut.
 
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