New Order Arrived

Littlemachineshop.com is a cool site with a lot of tools and accessories for the hobbyist machinist. This time I ordered:

  • Boring Bar Set, Carbide 3/8" Shank $15.95
  • Knurls, Fine Diamond $5.49
  • Dial Test Indicator, 0-15-0 x 0.0005" $29.95
  • Small Hole Gage Set, 4-Piece $12.95
  • Dovetail Cutter, 60° 3/4" Diameter $14.95>
  • Cutting Fluid, Re-Li-On 4oz $3.95>
  • Thin Parallels, 3" Long 4 Pairs $14.95


Boring Bar Set

Boring bars allows to work internal holes in the lathe or the mill.


This set has high endurance carbide tips. The dirty grease is to protect the shafts, that needs to fit fairly tight in the lathe or mill support.

Knurls

Mounted in a tool like scissors (there are other types), they make these pretty tiny rhombus finish some round handtools have.


Dial test indicator

This nice tool allows you to measure small deviations using a tiny ball end tip. A common use is to center the head of the mill to a piece with an already done hole, to enlarge or finish it.


Although cheap, doesn’t look bad. I wish to get a mitutoyo some day.

Small Hole Gage Set

This tools provide you a cheap method for measuring internal diameters. They has an expanding head, so you can copy the size of a hole an then measure it with a micrometer.


Well, I have to say that quality of this item is not very good. To be usable, I was to spend a couple hours with a file and sand paper (even one of the tips gets stuck). But for 13 bucks, you get what you pay for.

Dovetail Cutter

This type of end mill is used to cut these common”V” ways.


Tough it looks a bit rough, you will not find any cheaper, and looks great for occasional work.

Cutting Fluid

I usually use current oil (sometimes), but for harder materials a good cutting fluid would be a great help.

Thin Parallels

In pairs, these are usually used to rise a piece keeping parallelism to the base surface.


I took measures of every pair at two sides. This is the result:

A B Nominal
7/8″ 22.230-22.234 22.230-22.229 22,225
3/4″ 19.051-19.052 19.054-19.055 19,050
5/8″ 15.888-15.881 15.880-15.879 15,875
1/2″ 12.705-12.705 12.703-12.703 12,700

Not bad (parallelism is more important than nominal accuracy). The other sides are not very flat, but these are not supposed to be used. My only complaint: some box or bag would be great, as this type of tools must be handled and stored carefully (please note that my mic has 0.01 mm reading; the last digit was approximated by eye).OverallAll these are cheap tools, but fulfills in more or less grade the desired function. High quality tools will cost several times this ones; for example, a mitutoyo dial indicator will easily cost more than this whole pack. Also, as widely know, more importantly than the tool itself is how you use them.

A Lathe Project

This is a project I start to gain skills on design and metalworking. Usually I only do simple pieces.

1. The idea: A precision mini-drill aimed to drill pcb boards (only the drill, not stand). It will hold typical carbide drills with a mini collet and rotate to about 10.000 rpm. Future work will include doing a stand for manual drilling and, why not, using in an always wished cnc machine.

2. The draft: I start about two weeks ago doing some drawing in acad. Below is the current state.


Some tolerances are fairly tight (in the order of several um); for example, the fittings of the bearings must be done with a tolerance of 10 um or less.

I’m sure this is not the best design, with lot questionable things. But I’m also sure it would be a lot better than the cheap drill I actually use for pcb drilling (and even the dremel).

3. The first piece: And this is the first finished (almost) piece I do some days ago. It’s done on 2024 aluminium and looks pretty cool.


I’m satisfied with quality and precision. For example:

  • Diameter vary from to from 23.990 (front) to 23.983 (back). Maybe there’s a very slight misalignment of the spindle, fixable doing a simple adjust.
  • In the rear I measure 15.995 and the bearing fits without pressure, so interference fit was not achieved, but it’s ok.
  • Int the front, the bearing doesn’t fits easily; the measure I get from the hole is 15.975, so it’s a bit more tight than the target interference but I think that heating the piece will do the job. Thermal Expansion Coefficient Al 2024-T3 = 22.68 um/m C -> the hole will expand 18. 144 um raising temperature by 50 ºC.

I didn’t measure all sizes; only the critics ones.

4. The next: The next piece I want to do is the one in the center; but currently I don’t have the required tools (boring tools for deep hole), and after struggle myself if make or not the tools, I decided go the easy way and do an ebuy. May be meanwhile I try the main axis.

Overall

The more I detail the draft, the more find myself saying “how the hell will I do this piece?”. But that’s the idea.
Up to this time I have read several books on metalworking, but now I realize how different is theory and practice.