Here is a list of all the postings HOWARDT has made in our forums. Click on a thread name to jump to the thread.
|Thread: Odd furrow like finish when taper turning?|
If the gibs are loose it could be the tool tipping, ie rocking back and forth so altering tool depth. Make sure everything is tight but still movable. If you still get rocking r twisting then some remedial work is required to the slide and cross slide.
|Thread: Recommended paint for a FLB redwood external door?|
Paint, oil or varnish just make sure it is exterior grade for the material to be covered. Have painted many doors over the years and never had a problem. Occasionally pass by my fathers old house and I painted the garage door about 15 years ago and still looks the same. For yours, if it was me it would be a Osmo or Sadolin finish.
|Thread: Jones and Shipman 540 Dripping|
Use to heat black pudding in boiling water, now I cover in film and microwave, as said never fry it goes hard. Dripping on white bread no salt, pork is favourite. Lard on toast, maybe a little salt. Treats of bygone era, kids don’t know what they are missing.
|Thread: ER25 or MT2 Collets|
I have a Sieg SX2P 3MT and use an ER25 collet holder. Most of the time the maximum cutter I use is 8mm, I found this to be the sweet spot for metal removal and vibration. Almost never use the maximum 16mm and only use 1/2 inch for a dovetail cutter and 12mm for a fly cutter. ER25 gives me good visibilty around the cutter although I have raised the column by about 75mm as there seemed a lot of waster travel.
|Thread: Cast Iron stress relieving|
Where I worked, in Leicester, castings were kept outside. But this was in the days of reasonable volumes when buying a 100 or so of a part was no big deal. Move on twenty years and small volume and single castings, heat treatment of castings and fabrications. Lastly over the last years some vibrational stress relieving of fabrications and machining from solid rather than casting.
|Thread: Mixing Gear Module?|
In answer to the original question, yes you can mix the module or dp, but obviously in pairs. One thing to bear in mind though that gear power and wear are proportional to the module and number of teeth. So if you had a gear in the train of 18T at 1 mod it would need to be 36T at 0.5 mod, unless you use a stronger material. Using different tooth sizes will enable you to get odd ratios probably in smaller sizes, I.e using 127T at 0.5mod.
|Thread: Precision division plates|
Used many Hirth couplings over the years on rotary indexing applications, most were in the region of 600mm diameter. The parts carrying the two rings were guided in fairly loose plain bearings allowing the coupling to make position. The concept of the Hitrth coupling is that the accuracy increases slightly as the halves bed into each other. I mostly used the lower tooth counts too suit the index required which was usually multiples of two. Expensive pieces but simple. As well as two piece there are three piece which have an inner and an outer ring joined by a single ring on the other side, this allows one ring to remain in contact with the fixed ring at all times during indexing.
|Thread: EN1a vs EN3 steel|
I’ve used Rapid Metals near Coventry. Good selection, round, flat and angle in most metals and some plastic. Do bags of offcuts at good price general prices seem to have increased recently. Plenty of short lengths on racks but can cut easily enough.
|Thread: SX2p mill gas struts|
On my SX2P, 3MT, I weighed the head at around 15kg. I used two GS6-160-200 at £16 each. The assembly was made with the rods pointed down as required.
No he stated Swiss pattern not Swiss made, another option is USA pattern.
How would you know you were with a floosie in the Monte Carlo honeymoon suite if the dementia had kicked in 15 years previously?
|Thread: Quality issues with a SIEG SX2.7 mini mill|
As Andrew Johnston and probably others, accuracy depends on what you are trying to achieve. I was a machine tool designer for most of my working life. The accuracy required by any machine and fixtures. most usually there where more than one machining station and hence multiple work holding fixtures, was required to be a percentage of the produced component drawing tolerance. For those who like reading look up Sigma tolerance analysis. Machines were built with spacers and setting blocks to enable tweaking of position. Here of course I am talking of one off special machines.
European and USA designed standard machines were/are built using special machines in some cases to achieve part tolerances which when built into the final assembly achieve their standard tolerances. These machines in most cases where heavy cast iron floor mounted machines, built like the proverbial house. Over the last thirty years the CNC machines have largely took over where multiple hand operated machines stood, but these are still heavy duty machines. All these machines are built with the ability to achieve a final accuracy check, which may require a part to be re-machined or reset to achieve this.
Our hobby machines, I use a Sieg SC3 lathe and a SX2P which I bought three years ago, new. Both machines have been partially stripped for one reason or another more than once, and some improvements (as far as I am concerned) made in that time. But other than checking tailstock alignment, I haven't bothered with any other accuracy checks. Once you start chasing microns as a hobby machinist you would be better to walk away and find another hobby, you will never be satisfied. The drawings from LSBC or whoever have no tolerances, so if two bits fit together and look about right then that is it, What ever we produce is a kit of parts which with varying degrees of hand fitting may produce a finished working assembly. Alright in the past model engineers probably got a few of the more accurate parts produced on the side at work but they also had less accurate machines with no DRO, but any of these where probably time served indentured engineers. Work with what you have and strive to achieve the fits required by thoughtful processes.
Would I have done anything with this SX2.7, probably. If surface finishes are poor between two sliding faces then I would try to improve it. But if column squareness creates a problem on a machined part then is it the right machine process. Could the part be processed some other way to achieve a better end result.
If anybody wants to start up a UK manufacturing facility for designing and building hobby size machines then I am sure Ketan would support them so long as prices where compatible with our purses.
|Thread: SX2p mill gas struts|
I made a gas strut assembly to go inside the column, photo in my album. Been fitted and working for probably 18 months now. I think the struts were 6mm rod.
|Thread: Where to begin?|
3D CAD and CNC skills do not necessarily go together in the manufacturing world. You are either a CAD designer with all the theoretical skills and hopefully some machine shop skills or you are a CNC programmer/operator with the capability to read a drawing, which is 2 dimensional, or interpret a 3D model.
If you just want to work in your own workshop and design you own parts then the world is you oyster, so long as you have deep pockets. Moving from a free 3D CAD package to a professional licensed one runs to thousands a year in licence subscription. Then you need a CAM package that will create code for the selected machine.
Then again if you are a model maker, as most are here, with an interest in modelling and machining then you learn with a free 3D CAD package and later learn the machining side when you have a CNC machine. It would be a mistake to try to learn the two things together, programme errors on cnc cutting machines can prove costly in both tools and spindles.
For me I use Fusion 360, only because I am a life long Autodesk user, and use manual machines to produce parts. Would I like to have a small CNC machine to program, yes, but only for the parts which are more than two off. At the moment producing ten locomotive wheels from 110mm bar makes me wish I had CNC.
|Thread: Filling defects in slideways|
Devcon, that was the name I was trying to remember.
|Thread: releasing tapers|
For what it is worth. Locking tapers e.g. morse, create a friction lock by virtue of there shallow angle. An included angle of less than 14 degrees will provide a friction lock when tapped into place. But this lock will remain in place so long as the major force is along the centre of the taper. If vibration or/and side loads occur then the taper may release. The Morse taper or Brown and Sharpe taper are both available by design with a tang which is designed to allow disassembly of the inserted taper in a spindle by applying an angled drift. The tang has a clearance in the spindle slot of 0.010" nominal, with this in mind any rotational force will act as a point load initially on the tang. It is not uncommon on worn drill presses to find a number of drills with twisted tangs, Twisting seems to get worse as the taper size increases. probably due to the blacksmith element of the larger drilling machines. So using a locking taper with any vibrational tooling, such as milling cutter will require a draw bar. The drive tang gives a long contact face with the drift, a domed pin will give a line contact so deformation of the either the pin or the drift will occur at each release.
CNC and conventional metal cutting machines use a non locking taper with the drive being made by a couple of face keys. Retention being made by a draw bar through the spindle is locked either manually or by hydraulics and spring packs.
i'll stick with convention and accept that standards are there for a reason even if that reason has been lost in time. I am sure some one will find an original document showing why soon.
|Thread: Filling defects in slideways|
Having just had a look at the Diamant site I see they do something called Plasticmetal, appears to fulfil your needs.
I used or rather called for Moglice to be used for many years on machine tool designs. Moglice was always used on the moving face when in full contact with a metal surface, being cast iron or hardened steel with suitable lubrication system. It is a softish material and tends to chip if you catch the edge. So in my opinion not suitable for this application. I think you need to go with something like JB Weld, but perhaps with a higher metal filler content. I am sure we used to something for this application but I can't remember what.
|Thread: Parting off tool - straight or angled.|
I use the 1.5 x 10 M42 plain with angled sides. Much stronger than the plain hss bit.
|Thread: Issue Reading New Digital Viewer|
Just read through this thread and thought I would give the latest issue a try, 4605 ME. On my Mac desktop digital view is through a HTML 5 Reader, all works magnifies, no problems. Print a full page, right hand menu to select page to print, scale print down to print onto A4 single sheet, 75% to get it within the paper border on a laser printer, all ok. All reads OK on my iPad and iPhone, Windows 7 laptop sits in its bag unloved.
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