After all the control only needs to generate simple vector paths. I would also like to be able to sharpen my own tools and have looked at lots of designs and the price of commercial units and decided to build my own. It is still in the development stage at the moment using features which I have seen in other designs.
Another consideration is that, although cutters are relatively cheap, they are not necessarily there when you need them. That is, if you are into a job and find that you need a sharp, new cutter to replace the blunt one you have, you have to stop and go get one assuming you have a local supplier and he is open today.
With some kind of cutter grinder, sharp cutters are always available. You have two positions to grind a tool, on the flat end face of the 4" dished wheel or the periphery. End face first. To grind the RH side flute so the other flute is off the wheel in fresh air means you need to angle the cutter down. Something like 5 degrees for the cutting angle and 20 odd degrees for clearance but the movement is designed for a tip up attitude and not tip down.
In fact most wont go below 12 or 15 degrees and by the time you have the cutter sticking out the collet you have run out of room to actually fit it in.
Peripheral face next. Because the wheel head is at a fixed height and the same for the guide bar controlled collet system the angle that can be applied to the cutter is determined by how far out the cutter is.
Unlike a grinder with a column like a Quorn, Clarkson or Boxford these cannot place the wheel and cutter in the correct plane because they were not designed for this job - simples. Clive asks about a CNC version but Alan?
Pace did one in MEW that just sharpened the flutes and glossed over doing the ends. He states " Handwaving estimates suggest that sub Worden prices for something pretty versatile should be possible". I should say that I mainly build locos. I didn't use it that much because of the seeming endless supply of second hand endmills that came from factory closures, but I did start to use it,because I started to value the the quality of cut obtained from a super sharp end mill, and my "endless supplies" dried up when I moved.
I have now completed a 4 facit drill grinding jig, designed for the Stent, and I have to say it is now in almost daily use.
So, is it worthwhile to own one, the answer must be yes, if you are going to be a model engineer, rather than just using the machine tools to make odd items.
Although fairly green at the art and sometimes grit.. Now things are getting more interesting with more complex tasks, but Sharpening seems to generate large amounts of dust and dirt that are probably pretty abrasive, and very messy.
In a multi use workshop, dirt matters: swarf is bad enough, but the muck from the grinder is on a different scale. I am also concerned about fire risk, with hot sparks near various paints, solvents, gas, meths and occasional sawdust. I really don't want to set the grinder up permenantly in my small and mostly clean workshop, so I use it in a temporary rig outside, weather permitting.
Predictably, I have now fallen under the lure of indexable tips Availability of the sharp cutter is why we lust after the cutter grinders. I do not have one but have access to both a Deckle single lip cutter grinder and a Pratt and Whitney cutter grinder. I would pay good money to have one of my own but have never seen one for sale. Like Chris, I have never seen one for sale either. If you are lucky enough to track one down cheap look for the angled tool head and its set of rubberized collets otherwise its functionality will be drastically reduced.
Yes he is right ,the reasons why the ends were not included is because the machine uses the Quorn workhead and as such the ends can be sharpened on the Quorn. The ends could be done on the cnc machine but would it be really worth the effort to write an additional part to a file to do it. I don't think that some have grasped the difference of the type of cnc machines that are used for the production of new cutters and requirements of a similar machine in a model engineers shed.
A machine making new cutters picking up blanks ,loading and then grinding them all over and them returning them to the tray is somewhat different to rummaging around in an ice cream box to find an old cutter and returning it to a new cutting condition ,i do this all of the time.
The article for this machine was published in ,i had hoped that it may have given others some insipiration to work on something similar ,instead you see the same old methods used , here is an example from one such.
For this the cutter must also be set as shown in Sk. If, having sharpened the spiral cutting edges, the cutter fails to cut as you would like, almost certainly the clearance angle is insufficient.
For smaller cutters you may need to provide secondary clearance. Oh dear not very good is it. An excerpt taken from the text of a well known cutter grinding attachment. I feel that this not bad for a machine made mostly from scrap material, the main base is from two pieces of channel steel welded together.
Photo's in album "Quorn an cnc grinder". Obviously this machine has a much better operating system to be able to do this , something that would be unlikely to be seen in the home workshop and i expect beyond home workshop budgets. Getting back to th OP's original question ,I suppose it really depends on whether you are just out of your pram or a coffin dodger.
Hi Bandersnatch, you make a good point regarding availability of a sharp cutter when needed. But I would say most people carry more than one cutter of a particular or popular size and how often would the incidence of not having a cutter available occur? I have made some of the supplied accessories for the grinder, namely the four-facet drill jig and the slitting saw jig, Ref. It was whilst seeking advice on making these jigs from Kirk Burwell of Hemingway Kits that we discussed why it was necessary to make another work slide to accommodate the four-facet jig.
He suggested that as I had all the bits in front of me, I could explore the possibility of using only one work slide for all of the accessories. The original work slide uses a 40 tpi screw against an inserted button to push the tool holder forward, photo 6, whereas the drill jig uses a captive 40 tpi feed screw working in a nut in the jig base, photo 7.
As can be seen in the photos, there is a considerable difference in the location of the feed screw bearing block on these work slides. It was also decided to incorporate a Zero adjustable scale on the feed screw knob, photo 9. The numbers on the collar were stamped in the appropriate direction. It will be noted that due to the design of the various accessories, the distance from the bearing block varies. This variation is accommodated by making the respective adapters of a length to suit.
Once made and fitted, it is only necessary to release the grub screw in the adapter to allow the accessory to be slid off the feed nut which remains in place on the feed screw, and slide the next accessory onto the nut, locking it with the grub screw. The slide locking bolt fitted to the left-hand guide of the drill jig slide was also transferred to the work slide, as the normal lock screw strap has to be removed to fit some of the attachments. In fact this could now be left off altogether.
The feed screw locking method was retained. Having passed my conclusions on to Kirk, he very kindly adopted my modification and produced a CAD drawing for an adapter kit, which he intends to supply HK W. This was easily overcome by replacing the tenon with a piece of 1in. The tapped holes for the blade-retaining stud were replaced with a slot and a rebate to hold an M6 hex bolt captive, Fig 1. When I started using the four-facet drill grinding jig, it was found that the table had to be pulled right forward and there was a conflict with the drill clamping screw and the grinding wheel, photo Vertical slide parts list.
In order to grind radii of a known dimension on the end of lathe tools, I produced an auxiliary semi circular table to fit onto the Work Slide, photo In use the table is brought up to the grinding wheel and the feed collar zeroed. The table is then withdrawn by the required radius with the feed screw and the tool mounted to just touch the wheel. When grinding is started, the tool holder is moved back and forth following the curve of the table.
Radius table parts list. The above items are available from Hemingway kits. Magazine Locator. An unpleasant nocturnal experience. View All Topics. Community Sites. Model Flying Model Boats. Model Engineering Get Woodworking. No problem at all! Boring tools inserts can at long last be ground accurately as can slotting tools and parting blades. The Worden Mk3 is offered as a complete material kit, comprising all the pre-machined and welded sheet metal parts, ground and free cutting steel and alloy sections, fasteners, Aluminium Oxide taper cup Grinding Wheel, 3PDT Reversing Switch, Two Pole, Single Phase Motor v, 50Hz , glands, multi-core cable, drawings, wiring notes, illustrated constructional notes and user instructions.
If you'd prefer to get familiar with the simple construction and operation of the Worden before ordering HK , this item could be a wise first step.
When subsequently ordering the full kit, please contact us and we will discount what you have paid for the Drawing and Instruction Set. Please note that detailed drawings are not provided for the CNC pressed items which arrive complete in the material kit. Compared with conventional cone ground drills, 4 facetted drills require a marked reduction in drill pressure and show a reduced tendency for even long drills to wander.
The clearance angles chosen for the 2 cutting lips are those used by the late Professor Chaddock, namely 30 degrees for the first grinding then 10 degrees for the second and final grind.
Designed by Jim Whetren, this simple accessory provides an auxiliary table to allow you to add exact radii to your lathe tools. Perfect for fine finishing , thread cutting and form tools..
Utilising existing holes in the Worden's side plates, a feed screw and hand crank are added to provide more control when traversing.
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