Building a Mini-Tinker Cutter Grinder. End mill grinding

US2484590A. Universal end mill grinding fixture. Google Patents

Publication number US2484590A US2484590A US14963A US1496348A US2484590A US 2484590 A US2484590 A US 2484590A US 14963 A US14963 A US 14963A US 1496348 A US1496348 A US 1496348A US 2484590 A US2484590 A US 2484590A Authority US United States Prior art keywords sleeve collet standard end mill grinding fixture Prior art date 1948-03-15 Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) Expired. Lifetime Application number US14963A Inventor Leopold A Rocheleau Original Assignee Leopold A Rocheleau Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.) 1948-03-15 Filing date 1948-03-15 Publication date 1949-10-11 1948-03-15 Application filed by Leopold A Rocheleau filed Critical Leopold A Rocheleau 1948-03-15 Priority to US14963A priority Critical patent/US2484590A/en 1949-10-11 Application granted granted Critical 1949-10-11 Publication of US2484590A publication Critical patent/US2484590A/en 1966-10-11 Anticipated expiration legal-status Critical Status Expired. Lifetime legal-status Critical Current


  • 241000013987 Colletes Species 0.000 description 32
  • 102100014017 ODAM Human genes 0.000 description 2
  • 108060005663 ODAM Proteins 0.000 description 2
  • 238000010276 construction Methods 0.000 description 2
building, mini-tinker, cutter, grinder



  • B24B3/00 — Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools
  • B24B3/02 — Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of milling cutters
  • B24B3/025 — Tooth rests; Supporting means for milling-cutter grinding machines


UNIVERSAL END MILL GRINDING FIXTURE Filed March 15,1948 2 Sheets-Sheet l INVENTOR. L. ARocHzLmu Oct. 11, 1949. A. ROCHELEAU UNIVERSAL END MILL GRINDING FIXTURE 2 Sheets-Sheet 2 Filed March 15, 1948 I v INVENTOR. L. A. QocHaLEAu Patented Oct. 11, 1949 UNITED STATES PATENT OFFICE 2,484,590 UNIVERSAL ENDMILL GRINDING FIXTURE v Leopold A. Rocheleau, Leominster; Mass. Application March 15, 1948, Serial No. 14,963 I 4 g 1 7 Claims. (01. 51-225) This invention relates o a new and improved universal end mill grinding fixture which may be used to grind tools at either side of the grinding wheel and the main feature of which involves anv adjustable ring-like device clamped to a, head and having a guide finger thereon for guiding right or left end mills which are’fluted either right or left hand.

Further objects of the invention reside in the provision of a universal tool’grinding fixture including a construction which may be adjusted to grind right or left hand end mills on the flutes thereof to sharpen the same; for grinding the end of the end mills; for grinding endmillswith either left or right hand spirals, and for grinding tools at any angle.

Fig, 2 is a view similar to Fig. 1 but showing the device at the opposite side of the grinding wheel;

building, mini-tinker, cutter, grinder

As shown in the drawings. there is provided a base [U which is adapted to be secured to a machine bed by any desired or convenient means, such as the ears l2, which may be bolted to a machine bed or platen in desired relation to the grinding wheel i4 thereof.

Pivotally mounted on the base l0 there is a standard 16 which may be angularly adjusted about a vertical axis to any desired degree as indicated by the indicia 18 which appears on the base In, the standard l6 being provided with an index finger 20 so as to indicate the degree of anular departure from the zero position shown in Fi s. 1 and 2. The standard l8, of course, is provided with a clamping mechanism which may be of any usual or convenient kind.

The standard I6 rises as shown in Figs. 1 and 2 and is provided at its upper end with a rotary index plate 22 mounted on a horizontal axis 24 and adapted to be clamped in any rotative position desired about this axis. Integral with the plate 22 is a barrel or sleeve 26 which is, of course, angularly adjustable therewith. This sleeve slidingly and rotatinglv receives a collet 28 having an operating handle 30 for holding a tool 32 therein at 34 and also provided with a handle 36 for moving the collet in and out and rotatably in the sleeve 26. Indexing devices may, of course, be used with the collet.

Both ends of the sleeve 26 are milled out on a circle as indicated at 38 to receive a split ring All which may be clamped thereto as by means of a In the use of the apparatus, asshown in Fig.

1, the device is set for grinding right hand end mills with right hand spirals and the.set up of Fig. 2 shows grinding right hand end mills with a left hand spiral. The end mill 32 is inserted in the collet 28 and clamped therein by means of the thumbpiece 3i] and one of those spirals of the end mill is engaged with the top of the finger 52, whereupon the thumbpiece 36 is grasped to move the collet through the sleeve into engagement with the grinding wheel M, the end mill or another tool being ground and the collet being rotated by the engagement of the tool with the finger 52, so that a smooth even grinding cut is obtained.

In order to reset the device from the Fig. 1 position to the Fig. 2 position, the ring 40 may be placed in the other end of the sleeve and the collet 28 reversed or the entire device could be swung about its vertical axis on base I0.

It is also pointed out that the guide finger 52 may be swiveled half-way around to depend instead of rise up from its support 48 or it may be set at any angle if such is desired. The entire device may be set at to the position shown in Figs. 1 and 2, to grind the end of the end mill or it may be swiveled to any degree to grind any angle desired.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed otherwise than as set forth in the claims, but what I claim is:

A device of the class described comprising a base, a standard, means to swivel the standard on the base on a vertical axis, a sleeve swiveled on the standard on a horizontal axis, a tool holder slidably and rotatably mounted in the sleeve, a guide finger holder for the tool adjustably and removably mounted on the sleeve at each end having a-co11et type of 3. A universal tool grinding fixture comprising I a base, a standard thereon and.angularly adjust able with relation thereto on a vertical axis, a-

sleeve on the standard and angularly adjustable thereon in a horizontal axis, alcoll’et’ or the’like'” slidable in the sleeve, a ring adjustable on and removable from the sleeve at each end” thereof, and a rest in the form of a pin mounted on the ring to engage a’ spiral of a tool held in the collet.

4′; A universal toolgrinding fixture comprising a base; a-standard thereon and’angularly adjustable’ with relation thereto on a verticalaxis, a sleeve on thestandard and angularlyadjustable thereon in a horizontal axis, a collet or ‘the likeslidable in thesleeve, a ring rotatably ad- just’abl’e-on thesleevean’d a rest in the form of a pin mounted on the ringto engage a spiral of a tool held’ in’the collet, said’rest being revolvably mounted ontheringtodepend from the sleeve or to rise up therefrom;

5″; A universal’ tbol grinding fixture comprising aba’se;-a standard thereon and angularly adjust able with relation thereto on a vertical axis; a sleeve on ‘thestandard and angularly adjustable thereon ona horizontal axis; a collet orthelike sli’dable in the sleeve’and’ a rest in the=formof” s 4 a pin mounted on the sleeve to engage a spiral of a tool held in the collet, and a ring revolvable on the sleeve, the rest being secured in adjusted position on the ring.

A universal tool grinding fixture comprising a base, a standard thereon and angularly adjustable with relation thereto on a vertical axis, a sleeve on the standard and angularly adjustable-thereon on a horizontal-.axis, a collet or the like’slid’able in the sleeve and a rest in the form of a pin mounted on the sleeve to engage a spiral of-a tool held in the collet, and a ring revolvable on the sleeve, the rest being secured in adjusted position on-thering; said sleeve receiving the ring at either end selectively.

‘7. A universaltool grinding fixture comprising a base’ya standard thereon and angularly adjustable with relation thereto on a vertical axis, asleeve’ on the standard and angularly adjustable thereon on a horizontal axis, a collet or the like’s’lidable in the sleeve” and a rest-inthe’fo’rm of apin mounted on the sleeve to engage a spiral ofa tool held inthe collet; and a ringrevolvable on the sleevettlie rest being secured? in adjusted position’ on the ring;isaidfsleeve being circularly recessed at both end’s’to selectively receive the ring at eitherr’end and-pointingi either. upor down at either end for right and left hand endmills with :left” or righthand’ spirals;

US14963A 1948-03-15 1948-03-15 Universal end mill grinding fixture Expired. Lifetime US2484590A ( en )

Priority Applications (1)

Application Number Priority Date Filing Date Title
US14963A US2484590A ( en ) 1948-03-15 1948-03-15 Universal end mill grinding fixture

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US14963A US2484590A ( en ) 1948-03-15 1948-03-15 Universal end mill grinding fixture

Building a Mini-Tinker Cutter Grinder

The Mini-Tinker is a version of the Tinker Tool and Cutter Grinding Jig whose plans are sold by Guy Lautard. Plans and information for a very similar jig, the Raymac, appeared in Model Engineers Workshop serialized 9/2001 to 2/2002; this unit may be somewhat more capable than the Tinker. The jig holds the tool to be sharpened and allows applying it to a bench grinder wheel in a precise way. After studying the plans I decided to make a Mini-Tinker instead of the standard Tinker but scaled up the size of some parts to eventually allow sharpening cutters of 1/2 inch or more. Initially, I made the normal Mini-Tinker tool holder which is limited to cutters with shanks of 3/8 inch or less but I have the material for a larger tool holder block to be built after trial of the regular size block. Here is the back side. (Eventually I decided the Mini-Tinker wasn’t for me and built a Brooks-Stent which has worked out well.)

The Tinker is simpler than other cutter grinders (like the Stent and Quorn) and the Mini-Tinker is a further simplification of the underlying Tinker design. The difference is that the Mini-Tinker does not allow complete freedom in selecting the relief angles used in sharpening the teeth of end mills.- standard angles of 7 and 15 degrees are built in. The plans indicate these are the default angles used in most end mills so this suits my needs and makes it simpler and less error prone (for us absent minded types) than a jig where each of the angles must be selected and set each time a cutter is sharpened. Likewise, the slight angle where the outside of end mill blades are lower than the inside is fixed. This intelligence about how an end mill should be sharpened is built in via the wide slots milled into the tool holder block (the upper block in the picture); this block is rotated to select the appropriate slot for the part of the end mill being sharpened. Not all grinding angles are fixed so there is a setting gauge for the side (flute) relief angles plus an adjustment to set the centermost point to grind. I’ve only sharpened one end mill so far but this cutter, which was in poor shape, now seems to work fine. Lautard suggests MT2 collets to hold tools within a toolholder made from large drill rod; I expect to make multiple toolholders from drill rod instead because it is simpler and cheaper, mainly because I use only a few shank diameters.

Construction was not particularly difficult, possibly because I used a different (simpler) method to avoid the boring operations suggested in the plans to ensure alignment of the journals and bearings. The base is the first section constructed. The large holes are then fitted with plastic bearings: teflon, nylon, or delrin will do. The pivot shaft is 1/2″ drill rod and the holes in the base are 5/8. The base sides were rectangular pieces initially so I marked out the position of the holes to be drilled on one side piece. I drilled the holes in the base sides for the cross piece and tapped the holes in one side, drilled clearance holes for these two in the other side and then used 10-32 bolts to hold the side pieces together. The other holes were then drilled and the large holes were bored to size on the mill. The edges of the sides were also fly-cut while bolted together, thus ensuring they were identical; although this wasn’t really necessary it was easy to do once they were bolted together.

The base was carefully spotted to the sides, d/t 10-32 for bolting the sides to the bottom. Delrin bearings were turned with a slight taper in the outside so they would just start into the large holes bored in the base sides. The center of these bearings was bored to 0.488. The bearings were installed with a rubber mallet.- no epoxy or Loctite was necessary. One side was bolted to the base. The shank of a 1/2″ reamer was put through and the other side of the base was installed with the reamer trapped between the sides; the cross piece was also installed. Masking tape was wrapped around the shank of the reamer where it touched the bearing to ensure it was centered and the opposing bearing was hand reamed, which allowed the reamer to be extracted from the base. The reamer was turned around and run through the bearing by turning it backward (not allowed in a metal bearing but the plastic bearing didn’t hurt my reamer) and then the second bearing was reamed in the same manner. This simple scheme resulted in good alignment of the bearings with no need for line boring. The base sides were not removed after completion of reaming lest the bearing alignment be disturbed. The bearings were tighter than desired so the reamer was run through a couple times.

The tool holder block was done differently than the plans called for, instead adapting the method used for aligning the base bearings. The block was drilled from both ends on the mill/drill and the hole was enlarged by drilling and then a 1/2″ end mill was run in.- the end mill corrected any meandering by the drill. This hole was bored to 0.520 and then the ends were bored to 0.625 for 1/2 inch using a boring head in the mill. A delrin bearing was installed in one end; a short section of the bearing material was bored to fit the reamer shank and used to maintain alignment of the reamer while reaming this bearing. The second bearing was then installed and masking tape was placed on the reamer shank (as in aligning the base bearings) to ream the second bearing. The 1/2″ tool holder (made from drill rod) was tried and the reamer was run through the delrin bearings several times to obtain a low friction but shake free fit.


The first item I added to the Tinker tooling is a holder for the diamond used to true the wheel (shown at lower right in the picture). As usual this was made from mystery metal in my junk box; a 1/2″ piece (which had a 1/4″ spigot already) was cross drilled and then a 3/8 end mill was run through followed by a reamer. A set screw in the end retains the diamond holder’s 3/8 shank. The Tinker’s controls allow nice fine adjustment for truing the wheel.- the 90 degree fitting allows truing the wheel’s face and inserting the diamond holder alone allows truing the side of the wheel. I sharpen drills on the side of the wheel using a Pit Bull sharpener but hadn’t had a way of cleaning and truing it previously. The amount of material removed from the wheel was small, under 5 thousandths, but it produced noticable dust in the process; next time I’ll cover the Tinker with damp paper towels to minimize cleaning effort. In addition, I think a rubber shield could be added to help protect the Tinker from abrasive dust so that’s on my long (and growing) to-do list.

User Notes and Opinions

I find it helpful to remove the toolholder to judge progress on the tool being sharpened. When sharpening the helical flutes of 3/8 end mills, the knob on the toolholder prevents the toolholder from passing the toothrest finger (see the picture above). This prevents removing the toolholder unless the toothrest bracket is loosened, which changes the setup and requires re-setting. (The knob is needed on the 3/8 end to provide threads for the set screw.) The solution is to use a larger guideblock/toolholder so that a toolholder knob is not needed; the toolholder can then be withdrawn through the guide block (not possible with a knob installed). The regular toolholder can be withdrawn through the guideblock when sharpening 1/4″ tools because the knob is on the right.

The bench grinder used with the MiniTinker (or any similar sharpener) must be high quality with a well balanced wheel. Any vibration from the grinder will cause the sharpened edge to be slightly irregular. My bench grinder vibrates so I plan (eventually) to make a precision arbor for use with the Tinker.

The Mini-Tinker works well for making D bits and similar tools. It allows grinding the end to half diameter in an nicely controlled way and then, after re-setting, will grind the compound angled end to provide relief in both directions. Prior to the Mini-T, I had not been able to make a really satisfactory D bit. Countersinks are also feasible. End mills have been a problem for me.

The picture shows a new 2 flute end mill (with some of the protection still adhering); the primary clearance angle is marked “1”, secondary clearance is marked “2” and the third clearance is marked “3”. I measured angles on this cutter for these clearances as: 10, 21, 45 degrees. where the 45 degree angle is rotated to a different position. The Mini-Tinker has slots in the side of the tool block where it mates with the standard which set angles of 7 and 15 degrees for the primary and secondary clearance angles; the Tinker allows adjusting these angles.- the instructions recommend using 7 and 15. These angles likely work fine but they are not the angles found on any cutters I have purchased. As near as I can tell from Lautard’s instructions, there is no provision for grinding the third clearance angle using either the Tinker or Mini-Tinker. Without the ability to grind this third clearance angle, I haven’t figured out how to do more than touch up an end mill.

As a neophyte Mini-Tinker user, I very lightly touched up a couple of slightly dull end mills by grinding only the primary clearance and was happy with the performance. However, I have been unpleasantly surprised by the results of attempting to restore cutters where the tip of a tooth is chipped or heavily worn. In this situation, the land for the primary clearance widens from grinding so the secondary clearance must be ground also. However, when the secondary clearance is ground the center of the cutter widens; apparently, the third clearance angle needs to be ground too in order to accommodate grinding of the secondary clearance and I expect the angle of cutter rotation when re-grinding this angle needs to change too because the helical flutes have been shortened. (See Gashing using the Brooks.)

There is a possibility that I’m doing something wrong because in addition, the “dish” to the end teeth which causes the outer end of the teeth to be a couple of thou lower than the inner end isn’t there, i.e. the cutter end is flat. I checked the slot in the tool block for the depth difference from side to side and it is machined correctly so I added a couple of strips of masking tape on the shallow side to make it even shallower with no apparent result. I find this puzzling because the geometry intuitively looks correct so that it should work but the results don’t agree. The geometry is confusing because there are several slight angles included plus the movement of the tool is an arc rather than a straight line so it is hard for me to get it all straight in my mind.

My Mini-Tinker did not produce the expected relief angle on the helical edge of an end mill when I calibrated the setting gage as specified in the plans. The relief angle is also very dependent on the rotation angle of the cutter as set by the finger and this is difficult to judge accurately while using the MiniT.- a likely cause for this problem.

Bottom line: The Mini-Tinker, at least in my unskilled hands, won’t sharpen end mills.- the primary reason I built it. It is handy for D bits and counter sinks but I don’t make enough of these to justify the effort I put into construction. Eventually I gave up on it and built the Brooks-Stent.

Builder Notes

I believe the MiniTinker base, with some modification, will be adequate for use with the regular Tinker guideblock/toolholder. I like the MiniT base better than the Tinker base because the standard is supported between two bearings rather than cantilevered from a single bearing.- a matter of taste. I have been doing other things so I haven’t made a regular Tinker guideblock/toolholder to fit my MiniT base. The base was initially made larger than called for in the plans so it should be possible to do this in the future. The stop used to limit rotation doesn’t work well in that it is not precise.- it moves slightly from loosness in the thread.

The width of the bottom plate on my Mini-Tinker was increased from 2 inches to 3 inches. The width of the standard was increased from 0.75 inch to 1.5 inches. The pivot block length was increased from 1.75 inches to 2.75 inches. The guide block was increased from 2 inches to 2.75 inches (the Tinker guide block is 3 inches).

A machinist might complete the Mini-Tinker in about 20 hours; it took me over 30 hours plus time to study the plans. The plans are partly drawings but much information must be extracted from the instructions for the regular Tinker. The nature of the documentation would make construction more difficult for builders who are not fluent in English.

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