Taper Attachment Sillyness

[Fasttrack]

Hey guys

This is a pretty specific problem and it'll probably be hard to answer without actually being able to get your paws on it, but here it goes...

I've got this Lufkin Anti-friction taper attachment for one of my Pacemakers. The top slide rides on these two rails that are suspsended above the shoe and the pivot. When I reassembled everything, I noticed that the shoe is a tight fit - it slides fine but there is a little pad that doesn't quite clear the rails, so you have assemble the rails around the shoe. No biggie since the shoe never slides out from between the rails.

Then I put the top slide on and the gib strip binds up a lot sooner than it should - the slot for the adjusting screw is about 1.5" from flush. Also, the top slide remains (with or without the gib) above the bearing surface of the rail. It doesn't ride flat on them - this is possible due to a wonky feed screw. The screw itself is straight but the stub on the end is a little bit bent.

So has anyone else run into this problem or does anyone have any helpful tips?

Tomorrow, after a good night's sleep, I'll reinvestigate and hopefully find something obvious.

[beckley23]

Pictures would help.
Harry

[Fasttrack]

Well I think I found some problems ...

This morning I took it all back apart and started indicating the rails that form the dovetails. One rail was .01 higher at one end than the other end, with respect to the second rail. The second rail was more or less in line with the cross-slide dovetail, but I measured a concavity of about .005"

I took them both off and over to the surface plate where I use feeler gauges to get an idea of how badly they were warped. One passed a .010" gauge and the other passed .006 so after about two hours of careful pressing, I got them within .001 and now I'm going to mark them and see what they look like. I may try touching them up a bit with a scraper.

This taper attachment was made out-of-house by lufkin for ATW Pacemakers and it is the only part on this machine that has sucked to work on. The design seems sub-par compared to everything else on the machine.

I'll post pictures later this evening.

[Fasttrack]

Alright - so I'm thinking about modifying the shoe. I got the rails straightened out and the top piece slides beautifully. Unfortunately, it only slides until it hits the shoe and then it binds up.

Can I fly cut that little pad on the top of the shoe in order to clear the top piece?

The reason why it is higher is because that main table that everything slides on needed new bearings. I installed new bearings and spent several hours adjusting them so that they were all at the same height. I think, however, that I adjusted them to ride higher than they were previously. So now the shoe is higher and interfering with the topslide. I think a quick and easy solution would be to just shave about .005" off the top of the shoe.

Here are some pictures identifying the different pieces. I tried to use the same terms that the Pacemaker manual does.


A shot showing the two rails, the shoe, the pivot and the table.


You can see the results of the interference on the shoe. The first layer of paint has been scraped away.


This is one of the topslide / topiece

Here's one of just the pivot and the table...

[beckley23]

The problem with the "quick and easy" is that you don't know where else you're going to have to do more of the same. I had a similar problem on my Monarch, I decided the "quick and dirty" thing to do was go back in and redo the height of the bearings. These TA's can be a PITA to get right.
The TA is in the last half.
http://www.practicalmachinist.com/vb...oy-163406.html
Harry

[Fasttrack]

Damn - now I'm going to look bad if I don't go back and redo the bearings like you ... Best to do the job right, though ... <sigh>

BTW - how did you set the height of your bearings? Last time I used a straight edge and feeler gauges, but I'm thinking there is a better way...

(I'm about to look at the link you provided, so maybe there are some hints there about setting the height ...)

Thanks!

[Fasttrack]

The problem with the "quick and easy" is that you don't know where else you're going to have to do more of the same. I had a similar problem on my Monarch, I decided the "quick and dirty" thing to do was go back in and redo the height of the bearings. These TA's can be a PITA to get right.
The TA is in the last half.
http://www.practicalmachinist.com/vb...toy-163406.htm
Harry

PM sucks! I click your link and all I get is an advertisement about automated EDM. This new layout is horrible - all ads and no content ...

[beckley23]

Didn't know that would happen. Go into the Monarch forum on PM, the topic title is "Another New Toy".
There are 16 bearings in the Monarch TA that act as ways. 8 for the horizontal and 8 for the vertical. All of the bearings are mounted on eccentric studs. I set the 4 outer horizontal bearings first, moving the slide back and forth, then I set the inner 4. I had the slide matched parallel to the bed. After I had it all assembled, with the top hold down gibs attached, I coudn't slide it. I had to lower the slide about .005", so that it would slide with the gibs attached, and I don't know about the parallelism, but that shouldn't be to critical, because there is room for the shoe to float vertically. I'm not familiar with the details ATW TA's, except from the pictures you posted, but it looks like your shoe can float a bit, also.

Try the link now, I just edited it, and there was a slight change in the address from yesterday..
Harry

[Fasttrack]

Thanks! I got to the thread after a bit of searching last night. Alright, well I'll have to lower the slide and see how it goes...