Friday, November 19, 2010

Lathe Spindle Stop

darryl posted on the HSM forum about a spindle stop he made. I particularly liked the pin wrench for adjusting it:

A few pics of this simple project. The morse tapered stop piece with threaded adjustment bar, and the wrench to adjust it-

Inserted into the spindle taper-

With chuck in place- here it's set to give about 1/2 inch of material in the jaws behind the face of the jaws.

The diameter of the face on the adjusting bolt is just under 1/2 inch. There will be another adjusting bolt made if I need it to be a smaller diameter. The bolt is a friction fit, which I got by choosing a galvanized bolt over a chromed one. I polished up the bolt so it wouldn't chew up the threads in the pvc piece, and gave it a bit of grease. This was a carriage bolt, chosen to give enough of a head that I could machine it to give me a decent sized flat on the end. I also machined away the squared portion directly behind the head, reducing that diameter to 5/16 for this 3/8 bolt. That way I can screw it right in til it touches the plastic. It goes about as deep as I'll ever need it to, but if I do need it to be deeper, I can just cut off some of the plastic. The threads go in a bit over an inch, and the bore is drilled out from the other end to 3/8. No need to thread it all the way.

I could have simplified this and just used a normal bolt, but I wanted to be able to grip material down to about a half inch. This would have meant turning off the hex on the bolt head, leaving no way to adjust it. Otherwise I could simply have used a socket wrench. An alternative would have been to re-grind a hex head for a smaller socket, but I chose the pin wrench instead. If I need to use a smaller diameter adjusting bolt, I'll be forced to grind a hex onto it so I can adjust it. No way I'm going to cheap out and put a simple slot on the end of it. I hate those slippery flat blade screwdrivers.

Simple hold down

Zinom posted on the HSM forum about a simple hold down clamp he made:

Hey all, I often need to drill a hole in some thin stock that doesn't require a lot of precision so I don't like to spend much time on the set up.

*disclaimer* I use a small screwless vise almost exclusively so this may not be too useful to those with vises without vee grooves.

Threaded rod, scrap strap and a couple of set screws that fit in the vee groove to prevent the clamp from pulling upward.

Not a complex thing but for me it speeds up some operations and I hadn't seen anything similar in all the web surfing I've done.

This looked like a pretty handy thing to have. I think for a vise with V slot across it you could also use a rod for the bottom piece, and you wouldn't have to bother with the set screws. Also, a brass tip on the end of the thumbscrew would keep you from messing up the top of the vise.

Friday, August 13, 2010

Draw bar hammer

hornluv posted this draw bar hammer on the HSM forum. I thought it looked like a neat thing to make:

Here is a draw bar hammer I made. I used a 3/4" deep socket as the base of it. I machined a square on the brass insert and pressed it into the square on the socket. I then made a steel insert to take up all the empty space in the middle of the socket so I would have something to tap into. Drilled and tapped to 1/2-20 (The socket was hard-ish, but softer than I expected). Turned and knurled an Aluminum handle to fit and voila! Now I can loosen and tap in one fell swoop. Soon the world will be mine, mwahahaha!

Thursday, August 5, 2010

Digital Microscope

On the Home Shop Machinist forum, Evan posted a nifty microscope he made from a camera lens and a webcam:

Yep, Macro Scope, using ordinary camera lenses in macro mode. I have been taking micrographs by snapping pictures with a digital camera held to the eyepiece of my stereo microscope but isn't easy to achieve good focus and contrast. I decided to build something more suited to the job and easier to use.

It uses a generic 1.3 megapixel web cam. Various camera parts were used as well as a variety of raw materials. The base is flycut recycled HDPE that looks like black granite, the main column is a solid bar of extra hard mystery stainless steel that was .030 out of round to start. Gave a bit of pucker factor when I needed to drill and tap two 4-40 holes in it. The rack and pinon are machined from brass as are the supports for the twin lens adjustment rails. The elevating housing is made from acetal bar stock and the lens height/fine focuser screw is aluminum. It took a week of on/off time to make.

It can be dissassembled into 4 main components without tools in a few seconds. Different lenses may be attached via M 42 pentax screw mount or adapters. Long lenses (telephoto) work best because they give more distance to the subject for a given magnification and back focus distance.

Some sample images:

1: The edge of a broad radiused HSS cutter that I thought looked pretty good. That's why I built this device.

2: The point of a carbide graver that I hand sharpened on a diamond wheel. This is one of my best gravers for brass and it's because the flats are very symmetical.

3: An insert that looks ok to the eye but suddenly started cutting poorly.

4: The same type insert new. Note that the edge isn't very sharp.

To Do list includes an X-Y stage, measuring software overlays and an inserted illuminated back light in the base.

Evan later posted about a modification he made to it, replacing the webcam with an NTSC camera, and mounting a cheap LCD display on it.

I think that one of the inexpensive import granite comparator stands that Enco usually has on sale would work really well to base this on, if the size was right. You'd already have a solid base, and nice column, and fine adjustment mechanism. I think you could probably do a lot of things that you might use an optical comparator for with one of these, at least for simple HSM stuff. It would be easy to overlay a drawing of a gear tooth cutter on an image from this, and see how it compares.