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Atlas Cross Slide Replacement

3/19/2016

2 Comments

 
Picture
This was another casting I bought from Metal Lathe Accessories, as I mentioned before in the angle plate project.  I don't appear to have photographed the complete machining process.  The bulk of this was done on the CNC Bridgeport, so the hand programming was a bit painstaking.  First I decked all 6 sides flat and perpendicular using my (at that time recently acquired) Glacern 3" face mill.
What a joy it was, in combination with G-Wizard for feeds and speeds, to rip through that cast iron, hard skin and all.  I stalled it a few times (and crashed the machine) because I was too aggressive on the cut, but no harm done.  Then I put it upside down and machined the bottom side and the dovetails.  

After the dovetails were machined, I had to make up a set of angled wedges on the shaper (spread apart with threaded rods) to machine the gib.  This was done by spacing it up proud from the surface, machining until the edge was flat, flipping it upside down, and machining down to size so that it was just shy of the height of the dovetail.

Drilling for the gib adjustment screws was done next, to ensure that they broke into the gib slightly.  Everything was hand tapped, and we were set.  I bought a new cross slide nut via an eBay vendor, in the process discovering that I have an early 10" lathe, so the cross slide nut is different than the later 10" models.  This necessitated a second purchase.  The height of the boss for the cross slide nut was adjusted accordingly.

Prior to starting the machining of the cross slide, I made a spigot and t-slot nut for mounting the compound rest, per the supplied drawings.  There are no longer degree marks for the compound, but I didn't mind.  I already decided to make a replacement compound rest which would render this moot as long as you have an angle gauge in your measurement collection.

Adjustment of the gib once the cross slide was installed on the carriage was straightforward.  Even though there was some bow in the carriage due to use, the greatly extended cross slide made the bow irrelevant.  I expect some adjustment will be required as the carriage wears in, but this is likely to be slight.  If I was really ambitious, I might consider machining the carriage, but this seems unnecessary.  I couldn't be happier with how it turned out.
2 Comments
MRbob
7/22/2017 08:43:29 am

GREAT JOB... it looks simply fabulous.

I'm building one also, so a few questions.. of course!

How is it when using the lathe, did it make your cuts any better via things being stiffer? I plan on making a large block to mount my tool post that eliminates the compound and spans multiple t slots to try and gain stiffness as I have never used my compound.

I use a BXA tool post and it is not exactly the right height mounted on the stock compound so the block will be sized to take care of that and also have a nice LARGE t slot for the toolpost.

I am going to make a mount for my compound though, I bought a rotary table recently so of course, I got to use it and make up a degree'd base for the compound. I will just not keep the compound mounted unless I need it.

What size t slot and dove tail cutter did you buy? and would you be able to recommend a brand or have a source for the t slot cutter and dovetail cutter? 60 degrees for the dovetail right?

Also what size are your t slots? I'm guessing 1/2"

Thanks for any help and answers you might be able to provide.

Robert

Reply
Matt
7/22/2017 03:32:22 pm

Hi Robert,

Glad to hear from you! I found that the biggest problem I had was that the gibs could never be adjusted properly as a result of the wear. My machine had a hard life, and I should probably take the time to remachine the carriage and completely rework it. But haven't yet. When I'd attempt heavier cuts, the cross slide and compound would both slop around. I subsequently built a new compound from durabar (continuous cast iron bar) that should be covered elsewhere on the site which solved that problem. In combination, they dramatically improve the ability of the lathe to make use of the power. Now to make a new pulley so I can actually use the full 1/2 hp motor. The current one is pretty worn out! I also made an MLA rear mounted tool post. I wasn't sure how this would work out, but has also been a huge success for parting. Aside from the lost clearance for larger workpieces, it's been phenomenal. In combination with all the other new cast iron, it really has no problem with backlash at all, and really works beautifully. I can part and machine parts much more easily. Of course, a newish 14" Chinese lathe would probably work even better, but ...

So I don't remember the t-slot size, but it's whatever size takes a 5/16-18 threaded stud. The same size as is used on the Atlas 7B Shapers, so my t-slot kit is not useable for the lathe too. If I recall correctly, it's 7/16." If you bought the MLA cross slide kit, it should be in the plans.

As to the dovetail cutter, I think I started with a 3/8" 60 degree cutter, but it didn't have quite enough vertical cutting edge to form the whole cutter. I switched to a 3/4" cutter, and had to cut away some of the nut boss to make that work, but it's more than adequate as is. Your lathe probably uses the later type acme nut, so it may not be necessary to cut as much of the boss to get the dovetail formed.

Hope this helps! Feel free to ask away!

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