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darryl
02-06-2011, 08:47 PM
Just a thought- Yesterday I started building a tool-post platform. Today it's nearly finished. It's basically to eliminate the compound and allow a few different positions for the tool-post, eliminating sources of flex and play for when compound use is not needed. Anyway, I was thinking about a spray-on protective coating which would protect the bare steel, plus offer some grip for the tool post. My first thought was why not just use primer and leave it at that- if it develops worn spots, sand it off and re-apply. Anyone see a problem with that, or maybe recommend a better coating?

gvasale
02-06-2011, 09:00 PM
do you think chipped paint might become abrasive as the pigment is made out of something? Why not something like graphite grease, teflon grease or ?

It will give some protection maybe some sticktion too. It will make it messy.

I spray some preservative on exposed metal on my lathe. Turns somewhat brownish color, slightly gummy. Can tell you what it is tomorrow if you're interested. Not sure if its obsolete as you never know when "bargains" may be found.

Rosco-P
02-06-2011, 09:17 PM
How will the toolpost positively index the tool or toolholder with respect to the work? Are you thinking of pinning the base to the compound and having a limited number of "indexable" positions like a turret toolpost? Some type of ball detent between the lower and upper halves of the tool platform? Won't you miss the fine feed, provided by the compound?

darryl
02-07-2011, 03:18 AM
Firstly, I'm not tossing the compound, I'm making a simpler adapter for the tool-post. It just creates another flat surface to mount it on- one which is bolted to the crosslide slots. The post will have three positions it could be placed in, one nearer the chuck than I can currently put it, one in the middle which is basically where it lives now, and one closer to the tailstock. A bonus is that I can place it anywhere along the t-slots that suits- currently there's two spots where I can place the compound assembly and that quite often means that I'm running the crosslide so far forward that I expose the ways. The other problem is that I sometimes run out of room for the tool when the crosslide is cranked all the way back- then I have to get creative to be able to position the tool where I need it.

Nothing changes with the tool-post- the various holders and shims to allow correct tool height will be used as is. The post can be rotated and secured in any position just as is presently done on top of the compound. There is no indexing capability, and none wanted. I do intend to create a manual feed for the carriage, with a dial marked out in thous. This I would have done anyway, since there's no good way on this machine to advance the carriage by a precise amount. Normally you would use the compound for this, by setting it parallel to the ways, or off at some proper degree to allow a fine adjustment of position. This manual feed will move the carriage, so anything on it will move the same, and I'll be rid of the crosslide play and the flex in this 'less than optimum' arrangement. I might suggest to check out the 9x19 sites for some insight on this 'problem'.

I will still have the option to mount the compound assy and place the tool-post on it, using it as I have all these years. The new mount I'm making simply gives a more rigid and play-free base for the tool-post, when I don't want or need to use the compound. Plus I get the added benefits I mentioned earlier. I'm glad I have the t-slotted crosslide table, as it allows for lots of variations of tool holders.

My original question has only to do with friction between the tool-post and the base. As it is now, at times I need to use a pretty heavy torque on the securing bolt to prevent the tool-post from turning. Primer is not particularly slick, so I thought it might be a decent way to protect the metal as well as help keep the tool-post from turning once it's been tightened down.

Duffy
02-07-2011, 10:58 AM
Darryl, assuming that the platform is larger than the footprint of the tool post, is the bottom of the tool post truly flat? Perhaps, if it were slightly concave, when the bolt is torqued, the unit pressure on the perimeter bearing surface would be sufficient to lock it tight. This would also require that the tee-nut be as long as the tool post iswide to prevent tearing out the tee-slot.
Just a thought.

darryl
02-07-2011, 09:37 PM
This tool post is basically about 2 inches square, with a flat bottom. There are a few slots cut into the bottom, but for no reason other than possibly allowing a place for dust to go when you rotate it. Kind of like the little notches on a cylindrical square-

The bottom is and was flat, so theoretically it will touch down on any flat surface with equal contact pressure all over. In practice it will probably have a higher contact pressure where the central bolt is, but that's not something I need to worry about, as long as I get decent contact at the edges. The compound surface- I don't know if it's flat since the bolt is fixed to it. I could take it apart, remove the bolt, and check for flatness- not a bad idea if it's efficient to do, but even if I brought it back to truly flat, it still won't do anything to reduce flex and play in the compound. That is what I'm eliminating by having the option to mount the tool post to this accessory base that I'm building. The compound comes off, the other base goes on, the tool post goes on- away I go.

One thing I did consider doing is machining the new base a little lower than the bottom of the tool post needs to be, then fitting a sheet steel piece between the two. The extra piece could be thinner in the middle, and this would force the tool post to put pressure only around the edges for the best stability. I suppose I can make this change at any time, since all it would require is shaving the new base a little and making the shim piece.

Last nite I epoxied the base parts together, using the surface plate for alignment. I pre-drilled holes for the assembly bolts, so my next step is to drill those through, then tap the holes. If the epoxy holds long enough to get through that operation- then I take it apart, clean off the cheapoxy, degrease, then reassemble with the good stuff. I'm counting on the cheapoxy to let go fairly easily, so I won't have any problem with this procedure. Once it has been reassembled with good epoxy, I'll have to let it set overnite. I'll post a few pics then.

Boucher
02-08-2011, 03:33 PM
I use this long handle wrench to clamp my tool post down tight. It has never shifted in use.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0165Small.jpg


I made this block to interchange with the compound.

http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0191Small.jpg
This block was made to the same height as the compound so as to not require adjusting tool holders when changing back in forth. The t-slot is made deeper so there is more material above the nut to preclude any chance of it pulling out. Making a few trial parting cuts proves this to be more ridgid than using the compound.

I have allready had a case where the precision of compound for a fine facing was needed. This is just a two bolt swapout to get it back on.

The compound fits tightly on the center post and only contacts the cross slide surface in a band along the periphery The working area shows burnished and lack of contact can be seen in the darker old grease in the center.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0186Small.jpg

The tool post can be rotated/indexed in the same manner it normally is and the block can also be rotated just like the compound.